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 A155642 #14 Jun 13 2015 00:52:47 %S A155642 1,5,57,605,5937,55925,515817,4704845,42656097,385467365,3477018777, %T A155642 31332231485,282185395857,2540645125205,22870688939337, %U A155642 205860614516525,1852867600961217,16676418760213445,150090820599733497 %N A155642 9^n - 5^n + 1. %H A155642 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (15,-59,45). %F A155642 G.f.: 1/(1-9*x)-1/(1-5*x)+1/(1-x). E.g.f.: e^(9*x)-e^(5*x)+e^x. %F A155642 a(n)=14*a(n-1)-45*a(n-2)+32 with a(0)=1, a(1)=5 [From _Vincenzo Librandi_, Jul 21 2010] %o A155642 (PARI) a(n)=9^n-5^n+1 \\ _Charles R Greathouse IV_, Dec 22 2011 %K A155642 nonn,easy %O A155642 0,2 %A A155642 _Mohammad K. Azarian_, Jan 30 2009