A134090 - OEIS

A134090

Triangle, read by rows, where T(n,k) = [(I + D*C)^n](n,k); that is, row n of T = row n of (I + D*C)^n for n>=0 where C denotes Pascal's triangle, I the identity matrix and D a matrix where D(n+1,n)=1 and zeros elsewhere.

1, 1, 1, 3, 2, 1, 13, 9, 3, 1, 71, 46, 18, 4, 1, 456, 285, 110, 30, 5, 1, 3337, 2021, 780, 215, 45, 6, 1, 27203, 16023, 6167, 1729, 371, 63, 7, 1, 243203, 139812, 53494, 15176, 3346, 588, 84, 8, 1, 2357356, 1326111, 504030, 143814, 32376, 5886, 876, 108, 9, 1

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OFFSET

0,4

COMMENTS

Column 0 equals A122455 if we define A122455(0)=1.

LINKS

Table of n, a(n) for n=0..54.

FORMULA

T(n,k) = [x^(n-k)] Sum_{j=0..n} C(n,j)*x^j/(1-j*x)^k /[Product_{i=0..j}(1-i*x)].

EXAMPLE

Triangle T begins:

1, 1;

3, 2, 1;

13, 9, 3, 1;

71, 46, 18, 4, 1;

456, 285, 110, 30, 5, 1;

3337, 2021, 780, 215, 45, 6, 1;

27203, 16023, 6167, 1729, 371, 63, 7, 1;

243203, 139812, 53494, 15176, 3346, 588, 84, 8, 1;

2357356, 1326111, 504030, 143814, 32376, 5886, 876, 108, 9, 1; ...

Let P denote the matrix equal to Pascal's triangle shift down 1 row:

P(n,k) = C(n+1,k) for n>k>=0, with P(n,n)=1 for n>=0.

Illustrate row n of T = row n of P^n as follows.

Matrix P = I + D*C begins:

1, 1;

1, 1, 1;

1, 2, 1, 1;

1, 3, 3, 1, 1;

1, 4, 6, 4, 1, 1; ...

Matrix cube P^3 begins:

3, 1;

6, 3, 1;

13, 9, 3, 1; <== row 3 of P^3 = row 3 of T

30, 25, 12, 3, 1;

73, 72, 40, 15, 3, 1; ...

Matrix 4th power P^4 begins:

4, 1;

10, 4, 1;

26, 14, 4, 1;

71, 46, 18, 4, 1; <== row 4 of P^4 = row 4 of T

204, 155, 70, 22, 4, 1; ...

Matrix 5th power P^5 begins:

5, 1;

15, 5, 1;

45, 20, 5, 1;

140, 75, 25, 5, 1;

456, 285, 110, 30, 5, 1; <== row 5 of P^5 = row 5 of T.

PROG

(PARI) /* As generated by the g.f.: */ {T(n, k)=polcoeff(sum(j=0, n, binomial(n, j)*x^j/(1-j*x)^k/prod(i=0, j, 1-i*x+x*O(x^(n-k)))), n-k)} /* As generated by matrix power: row n of T equals row n of P^n: */ {T(n, k)=local(P=matrix(n+1, n+1, r, c, if(r==c, 1, if(r>c, binomial(r-2, c-1))))); (P^n)[n+1, k+1]}

CROSSREFS

Cf. columns: A134091, A134092, A134093; A134094 (row sums).

Sequence in context: A156628 A104980 A316566 * A132845 A129652 A154921

Adjacent sequences: A134087 A134088 A134089 * A134091 A134092 A134093

KEYWORD

nonn,tabl

AUTHOR

Paul D. Hanna, Oct 07 2007

STATUS

approved