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 A038579 #21 Jul 08 2025 22:24:34
%S A038579 1,4,10,28,64,140,304,640,1326,2716,5502,11052,22044,43700,86180,
%T A038579 169184,330810,644564,1251954,2424860,4684696,9029756,17368408,
%U A038579 33343520,63899686,122259372,233568998,445600236,849014964,1615709156,3071307852
%N A038579 Number of self-avoiding closed walks from 0 of area n in strip Z X {0,1,2}.
%D A038579 J. Labelle, Self-avoiding walks and polyominoes in strips, Bull. ICA, 23 (1998), 88-98.
%H A038579 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (2,1,0,-3,-2,-1).
%F A038579 G.f.: 2(1+2x^3+2x^4)/(1-x-x^2-x^3)^2-1 [Labelle]. - _Emeric Deutsch_, Apr 29 2004
%t A038579 CoefficientList[ Series[(2 + 4 x^3 + 4 x^4)/(1 - x - x^2 - x^3)^2 - 1, {x, 0, 28}], x]
%t A038579 LinearRecurrence[{2, 1, 0, -3, -2, -1}, {1, 4, 10, 28, 64, 140, 304}, 31] (* _Robert P. P. McKone_, Jan 28 2021, same method used in A038578 MMA *)
%o A038579 (PARI) Vec(2*(1+2*x^3+2*x^4)/(1-x-x^2-x^3)^2-1+ O(x^40)) \\ _Michel Marcus_, Jan 28 2021
%Y A038579 Cf. A022445, A038578.
%K A038579 nonn,walk,easy
%O A038579 0,2
%A A038579 _N. J. A. Sloane_
%E A038579 More terms from _Emeric Deutsch_, Apr 29 2004