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 A174836 #12 Feb 05 2019 04:45:05 %S A174836 1,4,16,46,124,310,748,1750,4012,9046,20140,44374,96940,210262,453292, %T A174836 972118,2075308,4412758,9349804,19748182,41593516,87381334,183151276, %U A174836 383079766,799713964,1666536790,3467291308,7203018070,14942907052,30959555926,64066595500,132428158294 %N A174836 a(n) = 1 + ((6*n-1)*2^n + (-1)^n)/3. %H A174836 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4, -3, -4, 4). %F A174836 G.f.: 1/(1-x) + 1/(3*(1+x)) - 1/(3*(1-2*x)) + 8*x/(1-2*x)^2. [_Richard Choulet_, Apr 04 2010] %F A174836 a(n) = 3*A113861(n+1) + 1. - _Michel Marcus_, Feb 05 2019 %o A174836 (PARI) a(n) = 1 + ((6*n-1)*2^n+(-1)^n)/3; \\ _Michel Marcus_, Feb 05 2019 %Y A174836 Cf. A113861. %K A174836 nonn,easy %O A174836 0,2 %A A174836 Fernando J. Ballesteros (fernando.ballesteros(AT)uv.es), Mar 30 2010 %E A174836 More terms from _Michel Marcus_, Feb 05 2019