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 A026219 #10 Jun 24 2025 13:13:26 %S A026219 1,2,5,3,9,4,13,6,17,7,21,8,25,10,29,11,33,12,37,14,41,15,45,16,49,18, %T A026219 53,19,57,20,61,22,65,23,69,24,73,26,77,27,81,28,85,30,89,31,93,32,97, %U A026219 34,101,35,105,36,109,38,113,39,117,40,121 %N A026219 Position of n in A026218. %C A026219 Is this a duplicate of A026201? - _R. J. Mathar_, Jun 24 2025 %F A026219 Conjectures from _Colin Barker_, Oct 15 2019: (Start) %F A026219 G.f.: x*(1 + 2*x + 4*x^2 + x^3 + 4*x^4 + x^5 + 3*x^6) / ((1 - x)^2*(1 + x)^2*(1 - x + x^2)*(1 + x + x^2)). %F A026219 a(n) = a(n-2) + a(n-6) - a(n-8) for n>8. %F A026219 (End) %K A026219 nonn %O A026219 1,2 %A A026219 _Clark Kimberling_