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 A056879 #12 Oct 11 2022 06:58:52 %S A056879 0,0,0,1,2,6,9,23,37,87,138,313,510,1130,1859,4070,6786,14750,24811, %T A056879 53715,91096,196769,335815,724470,1243175,2680212,4619999,9957652, %U A056879 17231447,37137177,64480255,138978282,242011375,521706359,910817416,1963885190,3436463468,7411495499,12995261895,28034824487 %N A056879 Number of n-celled axially symmetric polyominoes without holes. %H A056879 Tomás Oliveira e Silva, <a href="http://sweet.ua.pt/tos/animals.html">Enumeration of polyominoes</a> %Y A056879 Cf. A000105, A000104, A006746. %K A056879 nonn %O A056879 1,5 %A A056879 _N. J. A. Sloane_, Sep 03 2000 %E A056879 a(29)-a(40) from _John Mason_, Oct 11 2022