The On-Line Encyclopedia of Integer Sequences (OEIS)

A171509 revision #7

A171509

Riordan array (f(x), x*f(x)) where f(x) is the g.f. of A126931.

1, 3, 1, 10, 6, 1, 33, 29, 9, 1, 110, 126, 57, 12, 1, 366, 518, 306, 94, 15, 1, 1220, 2052, 1494, 600, 140, 18, 1, 4065, 7925, 6849, 3389, 1035, 195, 21, 1, 13550, 30030, 30025, 17628, 6635, 1638, 259, 24, 1

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OFFSET

0,2

COMMENTS

Equal to A053121*B^3, B = A007318.

LINKS

Table of n, a(n) for n=0..44.

FORMULA

Sum_[k, 0<=k<=n} T(n,k)*x^k = A126930(n), A126120(n), A001405(n), A054341(n), A126931(n) for x = -4, -3, -2, -1, 0 respectively.

T(n,k) = T(n-1,k-1) + 3*T(n-1,k) + sum_{i, i>=0} T(n-1,k+1+i)*(-3)^i. - DELEHAM Philippe, Feb 23 2012

EXAMPLE

Triangle begins : 1 ; 3,1 ; 10,6,1 ; 33,29,9,1 ; 110,126,57,12,1 ; ...

CROSSREFS

Cf. A053121, A054336, A096164, A171505

Sequence in context: A057967 A347258 A132964 * A171505 A134283 A035324

Adjacent sequences: A171506 A171507 A171508 * A171510 A171511 A171512

KEYWORD

nonn,tabl

AUTHOR

Philippe DELEHAM, Dec 10 2009

STATUS

approved