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 A210978 #17 Jun 18 2017 02:18:53 %S A210978 0,1,5,9,17,24,36,46,62,75,95,111,135,154,182,204,236,261,297,325,365, %T A210978 396,440,474,522,559,611,651,707,750,810,856,920,969,1037,1089,1161, %U A210978 1216,1292,1350,1430,1491,1575,1639,1727,1794,1886,1956,2052,2125,2225,2301 %N A210978 A186029 and positive terms of A001106 interleaved. %C A210978 Vertex number of a square spiral similar to A118277. %H A210978 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,2,-2,-1,1). %F A210978 a(n) = (3*(-1+(-1)^n)+2*(5+(-1)^n)*n+14*n^2)/16. a(n) = a(n-1)+2*a(n-2)-2*a(n-3)-a(n-4)+a(n-5). G.f.: -x*(2*x^2+4*x+1) / ((x-1)^3*(x+1)^2). - _Colin Barker_, Sep 15 2013 %o A210978 (PARI) Vec(-x*(2*x^2+4*x+1)/((x-1)^3*(x+1)^2) + O(x^100)) \\ _Colin Barker_, Sep 15 2013 %Y A210978 Members of this family are A093005, A210977, A006578, this sequence, A181995, A210981, A210982. %Y A210978 Cf. A001106, A118277, A186029, A195020, A195024. %K A210978 nonn,easy %O A210978 0,3 %A A210978 _Omar E. Pol_, Aug 03 2012 %E A210978 More terms from _Colin Barker_, Sep 15 2013