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 A173773 #15 Oct 08 2023 04:45:33
%S A173773 2,1,6,10,3,14,18,5,22,26,7,30,34,9,38,42,11,46,50,13,54,58,15,62,66,
%T A173773 17,70,74,19,78,82,21,86,90,23,94,98,25,102,106,27,110,114,29,118,122,
%U A173773 31,126,130,33,134,138,35,142,146,37,150,154,39,158,162,41,166
%N A173773 a(3*n) = 8*n+2, a(3*n+1) = 2*n+1, a(3*n+2) = 8*n+6.
%H A173773 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,2,0,0,-1).
%F A173773 G.f.: (1+x)*(2-x+7*x^2-x^3+2*x^4)/(1-x^3)^2.
%F A173773 Sum_{n>=0} (-1)^(n+1)/a(n) = (2-sqrt(2))*Pi/8. - _Amiram Eldar_, Oct 08 2023
%t A173773 Table[Sequence @@ {8*n+2, 2*n+1, 8*n+6}, {n, 0, 20}] (* _Amiram Eldar_, Oct 08 2023 *)
%Y A173773 Cf. A005408, A017089, A017137.
%K A173773 nonn,easy
%O A173773 0,1
%A A173773 _Paul Curtz_, Nov 26 2010