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 A004272 #13 Oct 24 2023 21:06:48
%S A004272 0,1,2,3,4,5,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,
%T A004272 44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78,80,82,84,86,88,
%U A004272 90,92,94,96,98,100,102,104
%N A004272 1, 3, 5 and the nonnegative even numbers.
%H A004272 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F A004272 G.f.: x*(x^2+1)*(x^4-x^2+1)/(x-1)^2.
%t A004272 Join[{1,3,5},2*Range[0,60]]//Sort (* _Harvey P. Dale_, Jul 10 2018 *)
%Y A004272 Cf. A004279.
%K A004272 easy,nonn
%O A004272 0,3
%A A004272 _N. J. A. Sloane_