This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A053484 #12 Mar 12 2017 12:27:40
%S A053484 1,3,5,19,7,109,331,155,2327,20947,34913,164591,691283,14977801,
%T A053484 314533829,4718007451,1572669151,16041225341,103122162907,
%U A053484 4571749222213,68576238333199,110777000384399,55582845806909,364345554264288511
%N A053484 Numerators in expansion of exp(2x)/(1-x).
%H A053484 G. C. Greubel, <a href="/A053484/b053484.txt">Table of n, a(n) for n = 0..400</a>
%F A053484 a(n) = Numerator[Sum[2^k/k!,{k,0,n}]]. - _Alexander Adamchuk_, Jul 22 2006
%t A053484 Numerator[Table[Sum[2^k/k!,{k,0,n}],{n,0,30}]] (* _Alexander Adamchuk_, Jul 22 2006 *)
%t A053484 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 *)
%o A053484 (PARI) for(n=0,25, print1(numerator(sum(k=0,n, 2^k/k!)), ", ")) \\ _G. C. Greubel_, Jan 18 2017
%Y A053484 Cf. A053485, A010842.
%K A053484 nonn,frac
%O A053484 0,2
%A A053484 _N. J. A. Sloane_, Jan 15 2000