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Triangle read by rows, numerators of coefficients (in rising powers) of rational polynomials P(n, x) such that Integral_{x=0..1} P'(n, x) = BernoulliMedian(n).
+10
7
0, 1, 0, 0, 0, 1, 0, 0, 0, 1, -1, 4, 0, 0, 0, 1, -3, 48, -12, 36, 0, 0, 0, 1, -7, 268, -176, 1968, -216, 64, 0, 0, 0, 1, -15, 240, -1580, 37140, -9900, 10400, -5760, 14400, 0, 0, 0, 1, -31, 4924, -11680, 488640, -238680, 496320, -639360, 5486400, -216000, 518400
FORMULA
T(n,k) = Numerator([x^k] Integral(Sum_{j=0..n}(-1)^(n-j)*Stirling2(n,j)*j!*x^j)^m) for m = 2, n >= 0 and k = 0..m*n+1.
EXAMPLE
Triangle starts:
[0, 1]
[0, 0, 0, 1]
[0, 0, 0, 1, -1, 4]
[0, 0, 0, 1, -3, 48, -12, 36]
[0, 0, 0, 1, -7, 268, -176, 1968, -216, 64]
[0, 0, 0, 1, -15, 240, -1580, 37140, -9900, 10400, -5760, 14400]
The first few polynomials are:
P_0(x) = x.
P_1(x) = (1/3)*x^3.
P_2(x) = (4/5)*x^5 - x^4 + (1/3)*x^3.
P_3(x) = (36/7)*x^7 - 12*x^6 + (48/5)*x^5 - 3*x^4 + (1/3)*x^3.
P_4(x) = 64*x^9 - 216*x^8 + (1968/7)*x^7 - 176*x^6 + (268/5)*x^5 - 7*x^4 +(1/3)*x^3.
Evaluated at x = 1 this gives a decomposition of the Bernoulli median numbers:
BM(0) = 1 = 1.
BM(1) = 1/3 = 1/3.
BM(2) = 2/15 = 4/5 - 1 + 1/3.
BM(3) = 8/105 = 36/7 - 12 + 48/5 - 3 + 1/3.
BM(4) = 8/105 = 64 - 216 + 1968/7 - 176 + 268/5 - 7 + 1/3.
MAPLE
# The function BG_row is defined in A290694. seq(BG_row(2, n, "num", "val"), n=0..12); # A212196seq(BG_row(2, n, "den", "val"), n=0..12); # A181131seq(print(BG_row(2, n, "num", "poly")), n=0..7); # A291447 (this seq.) seq(print(BG_row(2, n, "den", "poly")), n=0..9); # A291448
MATHEMATICA
T[n_] := Integrate[Sum[(-1)^(n-j+1) StirlingS2[n, j] j! x^j, {j, 0, n}]^2, x];
Trow[n_] := CoefficientList[T[n], x] // Numerator;
Table[Trow[r], {r, 0, 6}] // Flatten
Triangle read by rows, numerators of coefficients (in rising powers) of rational polynomials P(n, x) such that Integral_{x=0..1} P'(n, x) = Bernoulli(n, 1).
+10
6
0, 1, 0, 0, 1, 0, 0, -1, 2, 0, 0, 1, -2, 3, 0, 0, -1, 14, -9, 24, 0, 0, 1, -10, 75, -48, 20, 0, 0, -1, 62, -135, 312, -300, 720, 0, 0, 1, -42, 903, -1680, 2800, -2160, 630, 0, 0, -1, 254, -1449, 40824, -21000, 27360, -17640, 4480
COMMENTS
Consider a family of integrals I_m(n) = Integral_{x=0..1} P'(n, x)^m with P'(n,x) = Sum_{k=0..n}(-1)^(n-k)*Stirling2(n, k)*k!*x^k (see A278075 for the coefficients). Only omega(Clausen(n)) = A001221( A160014(n,1)) = A067513(n) coefficients are rational numbers if n is even. For odd n > 1 there are two rational coefficients. Let C_k(n) = [x^k] P_n(x), k > 0 and n even. Conjecture: k is a prime factor of Clausen(n) <=> k = denominator(C_k(n)) <=> k does not divide Stirling2(n, k-1)*(k-1)!. (Note that by a comment in A019538 Stirling2(n, k-1)*(k-1)! is the number of chain topologies on an n-set having k open sets.)
FORMULA
T(n, k) = Numerator(Stirling2(n, k - 1)*(k - 1)!/k) if k > 0 else 0; for n >= 0 and 0 <= k <= n+1.
EXAMPLE
Triangle starts:
[0, 1]
[0, 0, 1]
[0, 0, -1, 2]
[0, 0, 1, -2, 3]
[0, 0, -1, 14, -9, 24]
[0, 0, 1, -10, 75, -48, 20]
[0, 0, -1, 62, -135, 312, -300, 720]
The first few polynomials are:
P_0(x) = x.
P_1(x) = (1/2)*x^2.
P_2(x) = -(1/2)*x^2 + (2/3)*x^3.
P_3(x) = (1/2)*x^2 - 2*x^3 + (3/2)*x^4.
P_4(x) = -(1/2)*x^2 + (14/3)*x^3 - 9*x^4 + (24/5)*x^5.
P_5(x) = (1/2)*x^2 - 10*x^3 + (75/2)*x^4 - 48*x^5 + 20*x^6.
P_6(x) = -(1/2)*x^2 + (62/3)*x^3 - 135*x^4 + 312*x^5 - 300*x^6 + (720/7)*x^7.
Evaluated at x = 1 this gives an additive decomposition of the Bernoulli numbers:
B(0) = 1 = 1.
B(1) = 1/2 = 1/2.
B(2) = 1/6 = -1/2 + 2/3.
B(3) = 0 = 1/2 - 2 + 3/2.
B(4) = -1/30 = -1/2 + 14/3 - 9 + 24/5.
B(5) = 0 = 1/2 - 10 + 75/2 - 48 + 20.
B(6) = 1/42 = -1/2 + 62/3 - 135 + 312 - 300 + 720/7.
MAPLE
BG_row := proc(m, n, frac, val) local F, g, v;
F := (n, x) -> add((-1)^(n-k)*Stirling2(n, k)*k!*x^k, k=0..n):
g := x -> int(F(n, x)^m, x):
`if`(val = "val", subs(x=1, g(x)), [seq(coeff(g(x), x, j), j=0..m*n+1)]):
`if`(frac = "num", numer(%), denom(%)) end:
seq(BG_row(1, n, "num", "val"), n=0..16); # A164555seq(BG_row(1, n, "den", "val"), n=0..16); # A027642seq(print(BG_row(1, n, "num", "poly")), n=0..12); # A290694 (this seq.) seq(print(BG_row(1, n, "den", "poly")), n=0..12); # A290695# Alternatively:
T_row := n -> numer(PolynomialTools:-CoefficientList(add((-1)^(n-j+1)*Stirling2(n, j-1)*(j-1)!*x^j/j, j=1..n+1), x)): for n from 0 to 6 do T_row(n) od;
MATHEMATICA
T[n_, k_] := If[k > 0, Numerator[StirlingS2[n, k - 1]*(k - 1)! / k], 0]; Table[T[n, k], {n, 0, 8}, {k, 0, n+1}] // Flatten
Triangle read by rows, denominators of coefficients (in rising powers) of rational polynomials P(n, x) such that Integral_{x=0..1} P'(n, x) = Bernoulli(n, 1).
+10
6
1, 1, 1, 1, 2, 1, 1, 2, 3, 1, 1, 2, 1, 2, 1, 1, 2, 3, 1, 5, 1, 1, 2, 1, 2, 1, 1, 1, 1, 2, 3, 1, 1, 1, 7, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 2, 3, 1, 5, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 1, 1, 11, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1
FORMULA
T(n, k) = Denominator([x^k] Integral (Sum_{j=0..n} (-1)^(n-j)*Stirling2(n,j)*j!* x^j)^m) for m = 1 and k = 0..n+1.
EXAMPLE
Triangle starts:
[1, 1]
[1, 1, 2]
[1, 1, 2, 3]
[1, 1, 2, 1, 2]
[1, 1, 2, 3, 1, 5]
[1, 1, 2, 1, 2, 1, 1]
[1, 1, 2, 3, 1, 1, 1, 7]
[1, 1, 2, 1, 2, 1, 1, 1, 1]
MAPLE
T_row := n -> denom(PolynomialTools:-CoefficientList(add((-1)^(n-j+1)*Stirling2(n, j-1)*(j-1)!*x^j/j, j=1..n+1), x)): for n from 0 to 7 do T_row(n) od;
MATHEMATICA
T[n_] := Denominator[CoefficientList[Sum[(-1)^(n-j+1) StirlingS2[n, j-1] (j-1)! x^j/j, {j, 1, n+1}], x]];
Numerators of Integral_{x=0..1} P(n, x)^3 with P(n, x) = Sum_{k=0..n} (-1)^(n-k)* Stirling2(n, k)*k!*x^k.
+10
6
1, 1, 13, 1, 43, -61, 728877, 81739, -1779449713, -2112052153, 730622680308569, 113221320488699, -3660430816956396309, -3021604582205161, 21842539561810574341396283, 66747470298418575790593659, -124586733960451680357554181608419, -28471605423890788373026535240299
COMMENTS
Consider a family of integrals I(m, n) = Integral_{x=0..1} P(n, x)^m with P(n, x) = Sum_{k=0..n} (-1)^(n-k)*Stirling2(n, k)*k!*x^k. I(1, n) are the Bernoulli numbers A164555/ A027642, I(2, n) are the Bernoulli median numbers A212196/ A181131, I(3, n) are the numbers A291449/ A291450. The coefficients of the polynomials P(n, x)^m are for m = 1 A290694/ A290695, for m = 2 A291447/ A291448. (See A290694 for further comments.)
MAPLE
# Function BG_row is defined in A290694. seq(BG_row(3, n, "num", "val"), n=0..17);
MATHEMATICA
P[n_, x_] := Sum[(-1)^(n-k)*StirlingS2[n, k]*k!*x^k, {k, 0, n}];
a[n_] := Integrate[P[n, x]^3, {x, 0, 1}] // Numerator;
Denominators of Integral_{x=0..1} P(n, x)^3 with P(n, x) = Sum_{k=0..n}(-1)^(n-k)* Stirling2(n, k)*k!*x^k.
+10
6
1, 4, 140, 28, 20020, 4004, 6466460, 184756, 148728580, 29745716, 133706993420, 2431036244, 449741705140, 31885268, 670910837521540, 134182167504308, 409926521725660940, 4822664961478364, 1278006214791766460, 1921813856829724, 242081282475556183660, 4401477863191930612
MAPLE
# Function BG_row is defined in A290694. seq(BG_row(3, n, "den", "val"), n=0..20);
MATHEMATICA
P[n_, x_] := Sum[(-1)^(n-k)*StirlingS2[n, k]*k!*x^k, {k, 0, n}];
a[n_] := Integrate[P[n, x]^3, {x, 0, 1}] // Denominator;
Triangle read by rows, T(n, k) = [x^k](Sum_{k=0..n}(-1)^(n-k)*Stirling2(n, k)*k!* x^k)^2, for 0 <= k <= 2n.
+10
0
1, 0, 0, 1, 0, 0, 1, -4, 4, 0, 0, 1, -12, 48, -72, 36, 0, 0, 1, -28, 268, -1056, 1968, -1728, 576, 0, 0, 1, -60, 1200, -9480, 37140, -79200, 93600, -57600, 14400, 0, 0, 1, -124, 4924, -70080, 488640, -1909440, 4466880, -6393600, 5486400, -2592000, 518400
COMMENTS
Without squaring the sum in the definition one gets for the polynomials:
FORMULA
Integral_{x=0..1} P(n, x) = BernoulliMedian(n) = A212196(n)/ A181131(n).
EXAMPLE
Triangle starts:
[1]
[0, 0, 1]
[0, 0, 1, -4, 4]
[0, 0, 1, -12, 48, -72, 36]
[0, 0, 1, -28, 268, -1056, 1968, -1728, 576]
[0, 0, 1, -60, 1200, -9480, 37140, -79200, 93600, -57600, 14400]
The first few polynomials:
P_0(x) = 1
P_1(x) = x^2
P_2(x) = x^2 - 4*x^3 + 4*x^4
P_3(x) = x^2 - 12*x^3 + 48*x^4 - 72*x^5 + 36*x^6
P_4(x) = x^2 - 28*x^3 + 268*x^4 - 1056*x^5 + 1968*x^6 - 1728*x^7 + 576*x^8
MAPLE
P := (n, x) -> add((-1)^(n-k)*Stirling2(n, k)*k!*x^k, k=0..n)^2;
for n from 0 to 6 do seq(coeff(P(n, x), x, k), k=0..2*n) od;
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