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 A006773 M3959 #9 Nov 09 2018 16:23:01 %S A006773 0,1,5,30,186,1164,7344,46732,299604,1932900,12537542,81705782, %T A006773 534663812,3511466838,23136724382,152888000934,1012925595468, %U A006773 6726766841438,44767880394634,298522284224824,1994187071224056,13343458013982572,89420609914983270,600088861692380354,4032377457462571694,27129080022839863318,182726605700552001998 %N A006773 Sum of squared spans of 2n-step polygons on square lattice. %D A006773 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %H A006773 A. J. Guttmann and I. G. Enting, <a href="https://doi.org/10.1088/0305-4470/21/3/009">The size and number of rings on the square lattice</a>, J. Phys. A 21 (1988), L165-L172. %Y A006773 Cf. A006772. %K A006773 nonn %O A006773 1,3 %A A006773 _N. J. A. Sloane_ %E A006773 Name corrected, more terms from _Andrey Zabolotskiy_, Nov 09 2018