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A118805 G.f.: 1 = Sum_{n>=0} a(n)*x^n*Product_{k=1..n} (1-k*x)^2. 3
1, 2, 11, 106, 1506, 28736, 694719, 20452602, 712529978, 28746803264, 1320665162746, 68164569542628, 3909330000805268, 246855506805662816, 17030177827550184395, 1275139722566251183642, 103032621304705343054010 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vaclav Kotesovec, Table of n, a(n) for n = 0..32

EXAMPLE

1 = 1*(1-x)^2 + 2*x*((1-x)(1-2x))^2 + 11*x^2*((1-x)(1-2x)(1-3x))^2 + ... + a(n)*x^n*((1-x)(1-2x)(1-3x)...(1-n*x))^2 + ...

PROG

(PARI) {a(n)=if(n==0, 1, polcoeff(1-sum(k=0, n-1, a(k)*x^k*prod(j=1, k+1, 1-j*x+x*O(x^n))^2), n))}

CROSSREFS

Cf. A118804 (variant).

Sequence in context: A278070 A292428 A088690 * A198001 A207155 A292566

Adjacent sequences: A118802 A118803 A118804 * A118806 A118807 A118808

KEYWORD

nonn

AUTHOR

Paul D. Hanna, May 02 2006

STATUS

approved

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Last modified February 1 07:16 EST 2023. Contains 359981 sequences. (Running on oeis4.)