A053484 Numerators in expansion of exp(2x)/(1-x).

1, 3, 5, 19, 7, 109, 331, 155, 2327, 20947, 34913, 164591, 691283, 14977801, 314533829, 4718007451, 1572669151, 16041225341, 103122162907, 4571749222213, 68576238333199, 110777000384399, 55582845806909, 364345554264288511

Offset: 0

Author

N. J. A. Sloane, Jan 15 2000

Keywords

• nonn
• frac

Links

• G. C. Greubel, Table of n, a(n) for n = 0..400

Crossrefs

Cf. A053485, A010842.

Programs

Mathematica

Numerator[Table[Sum[2^k/k!,{k,0,n}],{n,0,30}]] (* Alexander Adamchuk, Jul 22 2006 *)
Numerator[Accumulate[Table[2^n/n!,{n,0,30}]]] (* or *) Numerator[ CoefficientList[ Series[Exp[2x]/(1-x),{x,0,30}],x] ] (* Harvey P. Dale, Mar 12 2017 *)

PARI

for(n=0,25, print1(numerator(sum(k=0,n, 2^k/k!)), ", ")) \\ G. C. Greubel, Jan 18 2017

Formula

a(n) = Numerator[Sum[2^k/k!,{k,0,n}]]. - Alexander Adamchuk, Jul 22 2006