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 A210977 #23 Jul 14 2015 10:35:25 %S A210977 0,1,3,7,11,18,24,34,42,55,65,81,93,112,126,148,164,189,207,235,255, %T A210977 286,308,342,366,403,429,469,497,540,570,616,648,697,731,783,819,874, %U A210977 912,970,1010,1071,1113,1177,1221,1288,1334,1404,1452,1525,1575,1651,1703,1782,1836,1918,1974,2059 %N A210977 A005475 and positive terms of A000566 interleaved. %C A210977 Vertex number of a square spiral similar to A085787. %C A210977 Partial sums of the sequence formed by A005843 and A016777 interleaved. %H A210977 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1). %F A210977 G.f.: -x*(1+2*x+2*x^2) / ( (1+x)^2*(x-1)^3 ). - _R. J. Mathar_, Aug 07 2012 %F A210977 a(n) = (10*n^2+6*n-1-(2*n-1)*(-1)^n)/16. - _Luce ETIENNE_, Oct 04 2014 %Y A210977 Members of this family are A093005, this sequence, A006578, A210978, A181995, A210981, A210982. %Y A210977 Cf. A000566, A005843, A016777, A085787, %K A210977 nonn,easy %O A210977 0,3 %A A210977 _Omar E. Pol_, Aug 03 2012