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A215990 Numerator of sum( k!/2^k, k=1..n ). 2
0, 1, 1, 7, 13, 7, 73, 461, 1721, 7391, 35741, 95833, 140902, 7208291, 6221977, 738064507, 5846167507, 49265043007, 440034922507, 4152348777757, 41275487330257, 431068442131507, 4718790944945257, 27013799863651691, 322866652557800441, 502628413904332477 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

If a(n) is even, then A215976(n)=0 (and n is listed in A215974); the converse is not necessarily true.

LINKS

Table of n, a(n) for n=0..25.

MATHEMATICA

Table[Numerator[Sum[k!/2^k, {k, n}]], {n, 0, 30}] (* Harvey P. Dale, Jul 02 2017 *)

PROG

(PARI) a(n)=numerator(sum(k=1, n, k!/2^k))

(PARI) s=0; for(k=1, 29, print1(numerator(s+=k!/2^k), ", "))

CROSSREFS

Sequence in context: A046163 A130770 A158622 * A122874 A066003 A115858

Adjacent sequences:  A215987 A215988 A215989 * A215991 A215992 A215993

KEYWORD

nonn

AUTHOR

M. F. Hasler, Aug 29 2012

STATUS

approved

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Last modified February 21 20:12 EST 2019. Contains 320377 sequences. (Running on oeis4.)