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 A276130 #19 Aug 27 2016 10:33:24 %S A276130 1,1,1,1,1,4,10,55,649,38881,6414706,24978826228,2913605221297249, %T A276130 112139525368095766797655,8403341152380185679389503620974065, %U A276130 146904111947501701959735285821948223340424963459227 %N A276130 a(0) = a(1) = a(2) = a(3) = a(4) = 1; for n>4, a(n) = ( a(n-1) +a(n-3) )*( a(n-2)+a(n-4) ) / a(n-5). %H A276130 Seiichi Manyama, <a href="/A276130/b276130.txt">Table of n, a(n) for n = 0..22</a> %F A276130 a(n) = (9-3*(-1)^n)/2*a(n-1)*a(n-3)-a(n-2)-a(n-4). %o A276130 (PARI) a(n) = if (n<=4, 1, (9-3*(-1)^n)/2*a(n-1)*a(n-3)-a(n-2)-a(n-4)); \\ _Michel Marcus_, Aug 27 2016 %Y A276130 Cf. A006721. %K A276130 nonn %O A276130 0,6 %A A276130 _Bruno Langlois_, Aug 21 2016