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 A113867 #13 May 22 2013 07:56:10
%S A113867 1,17,49,113,1137,3185,7281,72817,203889,466033,4660337,13048945,
%T A113867 29826161,298261617,835132529,1908874353,19088743537,53448481905,
%U A113867 122167958641,1221679586417,3420702841969,7818749353073,78187493530737
%N A113867 a(n) = a(n-1) + 2^(A047258(n)) for n>1, a(1)=1.
%H A113867 Vincenzo Librandi, <a href="/A113867/b113867.txt">Table of n, a(n) for n = 1..300</a>
%F A113867 G.f.: x*(1+16*x+32*x^2)/((-1+x)*(-1+4*x)*(1+4*x+16*x^2)). - _Vaclav Kotesovec_, Nov 28 2012
%t A113867 CoefficientList[Series[(1 + 16 x + 32 x^2) / ((-1 + x) (- 1 + 4 x) (1 + 4 x + 16 x^2)), {x, 0, 30}], x] (* _Vincenzo Librandi_, May 20 2013 *)
%Y A113867 Cf. A099974, A112627, A080355, A080567, A099969, A099970, A099971.
%K A113867 nonn,easy
%O A113867 1,2
%A A113867 _Artur Jasinski_, Jan 27 2006
%E A113867 Edited with better definition and offset corrected by _Omar E. Pol_, Jan 08 2009