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A193385 E.g.f. cosh( x^2 /2 ) / (1-x). 1
1, 1, 2, 6, 27, 135, 810, 5670, 45465, 409185, 4091850, 45010350, 540134595, 7021749735, 98304496290, 1474567444350, 23593081136625, 401082379322625, 7219482827807250, 137170173728337750, 2743403475221484075 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..20.

FORMULA

a(n) ~ cosh( 1/2 ) * n!.

a(n) = (A000266(n) + A130905(n)) / 2.

MATHEMATICA

With[{nn=30}, CoefficientList[Series[Cosh[x^2/2]/(1-x), {x, 0, nn}], x] Range[0, nn]!] (* Harvey P. Dale, May 01 2012 *)

PROG

(PARI) {a(n) = if( n<0, 0, n! * polcoeff( cosh( x^2 / 2 + x * O(x^n)) / (1 - x), n))}

CROSSREFS

Cf. A000266, A130905.

Sequence in context: A027213 A027237 A027245 * A030961 A030826 A030914

Adjacent sequences:  A193382 A193383 A193384 * A193386 A193387 A193388

KEYWORD

nonn

AUTHOR

Michael Somos, Jul 24 2011

STATUS

approved

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Last modified December 20 17:47 EST 2014. Contains 252272 sequences.