A185619 - OEIS

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A185619

G.f.: exp( Sum_{n>=1} (x^n/n)*Sum_{k=0..n} C(3n,3k)*x^k ).

1, 1, 2, 12, 41, 134, 535, 2100, 8008, 31483, 125405, 498762, 1995254, 8032580, 32433136, 131333532, 533489683, 2172483451, 8865550544, 36251329866, 148498309280, 609271648415, 2503419660325, 10299986121600, 42429641658643 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,3`
	LINKS	`Table of n, a(n) for n=0..24.`
	EXAMPLE	`G.f.: A(x) = 1 + x + 2x^2 + 12x^3 + 41x^4 + 134x^5 +...` `log(A(x)) = x(1+x) + x^2(1 + 20x + x^2)/2 + x^3(1 + 84x + 84x^2 + x^3)/3 + x^4(1 + 220x + 924x^2 + 220x^3 + x^4)/4 +...`
	PROG	`(PARI) {a(n)=polcoeff( exp(sum(m=1, n, sum(k=0, m, binomial(3m, 3k)x^k) x^m/m) +x*O(x^n)), n)}`
	CROSSREFS	`Cf. variant: A051286.` `Sequence in context: A098519 A127725 A280174 * A048014 A094702 A001621` `Adjacent sequences: A185616 A185617 A185618 * A185620 A185621 A185622`
	KEYWORD	`nonn`
	AUTHOR	`Paul D. Hanna, Mar 19 2011`
	STATUS	`approved`

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Last modified March 20 22:57 EDT 2023. Contains 361392 sequences. (Running on oeis4.)