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 A016218 #32 Sep 04 2017 03:43:10 %S A016218 1,10,71,440,2541,14070,75811,400900,2091881,10808930,55442751, %T A016218 282806160,1436400421,7271480590,36715316891,185008240220, %U A016218 930767824161,4676745613050,23475354034231,117743274047080,590182385739101,2956775990710310,14807336201610771 %N A016218 Expansion of 1/((1-x)*(1-4*x)*(1-5*x)). %H A016218 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (10,-29,20). %F A016218 From _Vincenzo Librandi_, Feb 10 2011: (Start) %F A016218 a(n) = a(n-1) + 5^(n+1) - 4^(n+1), n >= 1. %F A016218 a(n) = 9*a(n-1) - 20*a(n-2) + 1, n >= 2. (End) %F A016218 a(n) = 1/12 - 4^(n+2)/3 + 5^(n+2)/4. - _R. J. Mathar_, Mar 15 2011 %o A016218 (PARI) Vec(1/((1-x)*(1-4*x)*(1-5*x))+O(x^99)) \\ _Charles R Greathouse IV_, Sep 23 2012 %Y A016218 Cf. A016208, A000392, A000225, A003462, A003463, A003464, A023000, A023001, A002452, A002275, A016123, A016125, A016256. %K A016218 nonn,easy %O A016218 0,2 %A A016218 _N. J. A. Sloane_