Displaying 1-10 of 262 results found.
page
1
2
3
4
5
6
7
8
9
10
... 27
Side of primitive equilateral triangle with prime cevian p= A002476(n) cutting an edge into two integral parts.
+20
9
8, 15, 21, 35, 40, 48, 65, 77, 80, 91, 112, 117, 119, 133, 160, 168, 171, 187, 207, 209, 221, 224, 253, 255, 264, 280, 312, 323, 325, 341, 352, 377, 391, 403, 408, 425, 435, 440, 455, 465, 483, 504, 525, 527, 560, 576, 595, 609, 624, 645, 651, 665, 667, 703
COMMENTS
The edge a(n) is partitioned into q=s^2 - t^2= A088243(n)* A088296(n) and r=t(2s+t)= A088242(n)* A088299(n) by a cevian of length p. [Alternatively, (p,q,r) form a triangle with angle 2pi/3 opposite side p.] The quadruple {p,q,r,a(n)=q+r} satisfies the triangle relation: see A061281, or the simpler relation a(n)^2 = p^2 + q*r.
FORMULA
a(n) = A088241(n)* A088298(n) = s(s+2t), where s^2 + st + t^2, with s>t, form the primes p = 1 (mod 6) = A002476(n).
MATHEMATICA
sol[p_] := Solve[0 < t < s && s^2 + s t + t^2 == p, {s, t}, Integers];
Union[Reap[For[n = 1, n <= 10000, n++, If[PrimeQ[p = 6n + 1], an = s(s + 2t) /. sol[p][[1]]]; Sow[an]]][[2, 1]]] (* Jean-François Alcover, Mar 06 2020 *)
Values of y, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
2, 3, 3, 5, 4, 6, 5, 7, 8, 7, 8, 9, 7, 7, 10, 9, 12, 11, 11, 9, 13, 14, 11, 12, 15, 10, 12, 13, 17, 16, 11, 13, 17, 13, 17, 15, 12, 15, 20, 13, 18, 17, 21, 21, 18, 17, 21, 14, 21, 19, 24, 23, 19, 22, 15, 18, 20, 21, 19, 25, 18, 19, 23, 21, 27, 17, 27, 25, 19, 20, 27, 23, 28, 21, 26
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers]; Sow[y /. s[[1]]]]]][[2, 1]] (* Jean-François Alcover, Mar 07 2020 *)
Values of x, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
1, 1, 2, 1, 3, 1, 4, 2, 1, 3, 3, 2, 5, 6, 3, 5, 1, 3, 4, 7, 2, 1, 6, 5, 1, 9, 7, 6, 1, 3, 10, 8, 3, 9, 4, 7, 11, 8, 1, 11, 5, 7, 1, 2, 7, 9, 4, 13, 5, 8, 1, 3, 9, 5, 14, 11, 9, 8, 11, 3, 13, 12, 7, 10, 1, 15, 2, 6, 14, 13, 4, 10, 3, 13, 7, 17, 3, 7, 9, 13, 8, 11, 16, 15, 6, 3, 12, 17, 7, 9, 1, 3, 16
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers]; Sow[x /. s[[1]]]]]][[2, 1]] (* Jean-François Alcover, Mar 07 2020 *)
Values of x + y, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
3, 4, 5, 6, 7, 7, 9, 9, 9, 10, 11, 11, 12, 13, 13, 14, 13, 14, 15, 16, 15, 15, 17, 17, 16, 19, 19, 19, 18, 19, 21, 21, 20, 22, 21, 22, 23, 23, 21, 24, 23, 24, 22, 23, 25, 26, 25, 27, 26, 27, 25, 26, 28, 27, 29, 29, 29, 29, 30, 28, 31, 31, 30, 31, 28, 32, 29, 31, 33, 33, 31, 33
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers]; Sow[x + y /. s[[1]]]]]][[2, 1]] (* Jean-François Alcover, Mar 07 2020 *)
Values of y - x, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
1, 2, 1, 4, 1, 5, 1, 5, 7, 4, 5, 7, 2, 1, 7, 4, 11, 8, 7, 2, 11, 13, 5, 7, 14, 1, 5, 7, 16, 13, 1, 5, 14, 4, 13, 8, 1, 7, 19, 2, 13, 10, 20, 19, 11, 8, 17, 1, 16, 11, 23, 20, 10, 17, 1, 7, 11, 13, 8, 22, 5, 7, 16, 11, 26, 2, 25, 19, 5, 7, 23, 13, 25, 8, 19, 1, 26, 20, 17, 10, 19, 14, 5, 7, 23
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers];
Values of 2x + y, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
4, 5, 7, 7, 10, 8, 13, 11, 10, 13, 14, 13, 17, 19, 16, 19, 14, 17, 19, 23, 17, 16, 23, 22, 17, 28, 26, 25, 19, 22, 31, 29, 23, 31, 25, 29, 34, 31, 22, 35, 28, 31, 23, 25, 32, 35, 29, 40, 31, 35, 26, 29, 37, 32, 43, 40, 38, 37, 41, 31, 44, 43, 37, 41, 29, 47, 31, 37, 47, 46, 35
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers];
Values of x + 2y, where x^2 + xy + y^2=p (x<y) is a prime of the form 6n + 1 (= A002476).
+20
6
5, 7, 8, 11, 11, 13, 14, 16, 17, 17, 19, 20, 19, 20, 23, 23, 25, 25, 26, 25, 28, 29, 28, 29, 31, 29, 31, 32, 35, 35, 32, 34, 37, 35, 38, 37, 35, 38, 41, 37, 41, 41, 43, 44, 43, 43, 46, 41, 47, 46, 49, 49, 47, 49, 44, 47, 49, 50, 49, 53, 49, 50, 53, 52, 55, 49, 56, 56, 52, 53
MATHEMATICA
Reap[For[n = 1, n <= 200, n++, If[PrimeQ[p = 6 n + 1], s = Solve[x^2 + x y + y^2 == p && 0 < x < y, {x, y}, Integers];
Semiprimes p*q where both p and q are primes of the form 6n+1 ( A002476).
+20
6
49, 91, 133, 169, 217, 247, 259, 301, 361, 403, 427, 469, 481, 511, 553, 559, 589, 679, 703, 721, 763, 793, 817, 871, 889, 949, 961, 973, 1027, 1057, 1099, 1141, 1147, 1159, 1261, 1267, 1273, 1333, 1339, 1351, 1369, 1387, 1393, 1417, 1477, 1501, 1561, 1591
COMMENTS
These are the products of terms from A107890 excluding multiples of 3. Every semiprime not divisible by 2 or 3 must be in one of these three disjoint sets:
A108172 = the product of a prime of the form 6n+1 and a prime of the form 6n-1.
The product of two primes of the form 6n+1 is a semiprime of the form 6n+1.
REFERENCES
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards Applied Math. Series 55, 1964 (and various reprintings), p. 870.
LINKS
M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical Functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972 [alternative scanned copy].
FORMULA
{a(n)} = {p*q where both p and q are in A002476}.
MAPLE
N:= 2000: # To get all terms <= N
P:= select(isprime, [seq(i, i=7..N/7, 6)]):
sort(select(`<=`, [seq(seq(P[i]*P[j], j=1..i), i=1..nops(P))], N)); # Robert Israel, Dec 27 2018
MATHEMATICA
With[{nn=50}, Take[Times@@@Tuples[Select[6*Range[nn]+1, PrimeQ], 2]// Union, nn]] (* Harvey P. Dale, May 20 2021 *)
Decimal expansion of Product_{k>=1} (1 + 1/ A002476(k)^3).
+20
6
1, 0, 0, 3, 6, 0, 2, 5, 4, 0, 2, 2, 1, 2, 5, 9, 8, 9, 6, 7, 0, 4, 3, 2, 3, 9, 3, 3, 3, 3, 2, 1, 8, 7, 8, 5, 9, 1, 7, 0, 5, 3, 9, 4, 7, 7, 1, 1, 7, 5, 0, 8, 7, 2, 1, 3, 7, 0, 2, 2, 4, 0, 2, 6, 4, 1, 6, 5, 2, 3, 7, 1, 7, 3, 7, 1, 7, 3, 6, 2, 6, 1, 4, 6, 6, 2, 7, 5, 2, 0, 4, 0, 8, 1, 5, 1, 4, 8, 2, 9, 8, 9, 1, 5, 7
COMMENTS
In general, for s > 0, Product_{k>=1} (1 + 1/ A002476(k)^(2*s+1)) / (1 - 1/ A002476(k)^(2*s+1)) = sqrt(3) * (2*Pi)^(2*s + 1) * zeta(2*s + 1) * A002114(s) / ((2^(2*s + 1) + 1) * (3^(2*s + 1) + 1) * (2*s)! * zeta(4*s + 2)). For s > 1, Product_{k>=1} (1 + 1/ A002476(k)^s) / (1 - 1/ A002476(k)^s) = (zeta(s, 1/6) - zeta(s, 5/6))*zeta(s) / ((2^s + 1)*(3^s + 1)*zeta(2*s)). For s > 1, Product_{k>=1} (1 + 1/ A002476(k)^s) * (1 + 1/ A007528(k)^s) = 6^s * zeta(s) / ((2^s + 1) * (3^s + 1) * zeta(2*s)). For s > 0, Product_{k>=1} (( A007528(k)^(2*s+1) - 1) / ( A007528(k)^(2*s+1) + 1)) * (( A002476(k)^(2*s+1) + 1) / ( A002476(k)^(2*s+1) - 1)) = 6 * A002114(s)^2 * (4*s + 2)! / ((2^(4*s + 2) - 1) * (3^(4*s + 2) - 1) * Bernoulli(4*s + 2) * (2*s)!^2) = Bernoulli(2*s)^2 * (4*s + 2)! * (zeta(2*s + 1, 1/6) - zeta(2*s + 1, 5/6))^2 / (8*Pi^2 * (2^(4*s + 2) - 1) * (3^(4*s + 2) - 1) * Bernoulli(4*s + 2) * (2*s)!^2 * zeta(2*s)^2).
EXAMPLE
1.0036025402212598967043239333321878591705394771...
Decimal expansion of Product_{k>=1} (1 - 1/ A002476(k)^3).
+20
6
9, 9, 6, 4, 0, 1, 6, 9, 2, 8, 1, 6, 0, 3, 6, 6, 3, 2, 2, 6, 2, 3, 6, 1, 1, 2, 2, 3, 8, 4, 7, 1, 8, 7, 9, 9, 9, 6, 5, 5, 7, 3, 8, 1, 8, 7, 1, 4, 0, 5, 3, 1, 5, 3, 7, 8, 6, 9, 8, 8, 9, 7, 4, 9, 3, 0, 1, 5, 9, 1, 3, 3, 2, 5, 3, 4, 3, 0, 6, 8, 4, 2, 5, 6, 2, 1, 9, 1, 9, 7, 2, 9, 9, 7, 7, 5, 2, 3, 2, 2, 1, 2, 3, 0, 1, 9
COMMENTS
In general, for s > 0, Product_{k>=1} (1 + 1/ A002476(k)^(2*s+1)) / (1 - 1/ A002476(k)^(2*s+1)) = sqrt(3) * (2*Pi)^(2*s + 1) * zeta(2*s + 1) * A002114(s) / ((2^(2*s + 1) + 1) * (3^(2*s + 1) + 1) * (2*s)! * zeta(4*s + 2)). For s > 1, Product_{k>=1} (1 + 1/ A002476(k)^s) / (1 - 1/ A002476(k)^s) = (zeta(s, 1/6) - zeta(s, 5/6))*zeta(s) / ((2^s + 1)*(3^s + 1)*zeta(2*s)). For s > 1, Product_{k>=1} (1 - 1/ A002476(k)^s) * (1 - 1/ A007528(k)^s) = 6^s / ((2^s - 1)*(3^s - 1)*zeta(s)).
EXAMPLE
0.996401692816036632262361122384718799965573818714...
Search completed in 0.165 seconds
| 