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 A091905 #7 Mar 08 2021 12:17:24 %S A091905 1,0,32,128,1536,10240,90112,688128,5636096,44564480,358612992, %T A091905 2860515328,22917677056,183207198720,1466194460672,11727408201728, %U A091905 93827855548416,750588484648960,6004845316145152,48038212773347328 %N A091905 Expansion of (1-4x)/((1+4x)(1-8x)). %H A091905 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (4,32). %F A091905 a(n)=8^n/3+2(-4)^n/3 = 32*A091904(n-1). %F A091905 a(n) = 4^n*A078008(n). - _R. J. Mathar_, Mar 08 2021 %K A091905 easy,nonn %O A091905 0,3 %A A091905 _Paul Barry_, Feb 10 2004