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 A002976 M0034 #23 Dec 27 2018 07:57:25 %S A002976 0,1,0,2,0,5,9,21,42,76,174,396,888,2023,4345,9921,22566 %N A002976 Number of certain self-avoiding walks with n steps on square lattice (see reference for precise definition). %D A002976 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A002976 W. A. Beyer, <a href="/A005208/a005208.pdf">Letter to N. J. A. Sloane, 1980</a> %H A002976 W. A. Beyer and M. B. Wells, <a href="http://dx.doi.org/10.1016/0097-3165(72)90024-6">Lower bound for the connective constant of a self-avoiding walk on a square lattice</a>, J. Combin. Theory, A 13 (1972), 176-182. %F A002976 a(n) = A006142(n)+2*A006143(n)+A006144(n). - _R. J. Mathar_, Oct 22 2007 %Y A002976 Cf. A001411, A037245. %K A002976 nonn,walk,more %O A002976 4,4 %A A002976 _N. J. A. Sloane_