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 A363090 #19 Nov 21 2024 19:25:11 %S A363090 1,3,12,52,237,1113,5339,26011,128247,638346,3201967,16164384, %T A363090 82044151,418352107,2141761669,11003117220 %N A363090 Number of 3-dimensional directed animals of size n. %C A363090 Fixed 3-dimensional fixed polycubes with neighborhood vectors [1, 0, 0], [0, 1, 0], and [0, 0, 1]. %C A363090 A005773 is the 2-dimensional equivalent: fixed polyominoes with neighborhood vectors [1, 0] and [0, 1]. %C A363090 Using neighborhood vectors [+-1, 0, 0], [0, +-1, 0], and [0, 0, +-1] gives A001931. %Y A363090 Cf. A005773. %K A363090 nonn,hard,more %O A363090 1,2 %A A363090 _Joerg Arndt_ and _Márk Péter Légrádi_, May 19 2023 %E A363090 a(14)-a(16) from _Johann Peters_, Nov 21 2024