A215990 Numerator of sum( k!/2^k, k=1..n ).

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

Offset: 0

Author

M. F. Hasler, Aug 29 2012

Keywords

• nonn

Comments

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

Programs

Mathematica

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

PARI

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

PARI

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