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A108994 Third diagonal of triangle A108990, in which the g.f. of row n, R_n(x), satisfies: [x^k] R_{n+1}(x) = [x^k] (1 + x*R_n(x))^(n+1) for k=0..n+1. 6
1, 3, 18, 180, 2670, 54096, 1411228, 45421776, 1747674405, 78485504845, 4037946005808, 234494393383614, 15187062546935643, 1086079262127563445, 85049134680670591560, 7241328591814507465712, 666283956766298002183275 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

a(n) is divisible by (n+1)*(n+2)/2.

LINKS

Table of n, a(n) for n=0..16.

FORMULA

a(n) = A108990(n+2, n) for n>=0. a(n) = (n+2)/2*A108995(n) for n>=0.

PROG

(PARI) {a(n)=local(F=1+x*O(x^n)); for(m=1, n+2, F=(1+x*F)^m); polcoeff(F, n)}

CROSSREFS

Cf. A108990, A108991, A108992, A108993, A108995, A108996.

Sequence in context: A223895 A111465 A247029 * A006472 A132853 A259666

Adjacent sequences:  A108991 A108992 A108993 * A108995 A108996 A108997

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 15 2005

STATUS

approved

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Last modified November 15 19:54 EST 2018. Contains 317240 sequences. (Running on oeis4.)