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 A049540 #9 Aug 24 2023 12:05:10 %S A049540 1,1,1,3,5,17,55,267,1467,10371 %N A049540 Number of n-ominoes for a high-dimensional orthoplex. %C A049540 An orthoplex polyomino does not extend more than two units along any axis. %e A049540 There are a(5)=5 orthoplex pentominoes: the two 3-D pentominoes that fit in a 2 X 2 X 2 box and the three 4-D pentominoes. %Y A049540 A005519 counts a superset. %K A049540 hard,more,nice,nonn %O A049540 1,4 %A A049540 _Robert A. Russell_