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 A105076 #16 Oct 13 2019 07:44:51 %S A105076 0,1,2,11,19,90,153,712,1208,5609,9514,44163,74907,347698,589745, %T A105076 2737424,4643056,21551697,36554706,169676155,287794595,1335857546, %U A105076 2265802057,10517184216,17838621864,82801616185,140443172858,651895745267 %N A105076 Numbers k such that 60*k^2 + 60*k + 1 is a square. %F A105076 From _R. J. Mathar_, Nov 13 2009: (Start) %F A105076 a(n) = a(n-1) + 8*a(n-2) - 8*a(n-3) - a(n-4) + a(n-5). %F A105076 G.f.: x^2*(1+x+x^2)/((1-x)*(x^4-8*x^2+1)). (End) %Y A105076 Cf. A103200, A001090. %K A105076 nonn %O A105076 1,3 %A A105076 _Pierre CAMI_, Apr 06 2005 %E A105076 Partially edited by _Jon E. Schoenfield_, Oct 13 2019