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A171776 E.g.f.: A(x) = exp( Sum_{n>=1} 2^(n(n-1)) * x^n/n ). 1
1, 1, 5, 141, 25161, 25295385, 129002055885, 3167498196303525, 363195624958803434385, 190409085693362565632615985, 449225585595812339036501379506325 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..10.

FORMULA

a(n) = A155200(n)*n!/2^n and is odd for n>=0.

EXAMPLE

E.g.f.: A(x) = 1 + x + 5*x^2/2! + 141*x^3/3! + 25161*x^4/4! +...

log(A(x)) = x + 4*x^2/2 + 64*x^3/3 + 4096*x^4/4 + 1048576*x^5/5 +..

PROG

(PARI) {a(n)=n!*polcoeff(exp(sum(m=1, n+1, 2^(m*(m-1))*x^m/m)+x*O(x^n)), n)}

CROSSREFS

Cf. A155200.

Sequence in context: A203523 A006269 A066264 * A277401 A208874 A222289

Adjacent sequences:  A171773 A171774 A171775 * A171777 A171778 A171779

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jan 20 2010

STATUS

approved

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Last modified January 21 08:09 EST 2020. Contains 331104 sequences. (Running on oeis4.)