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 A359522 #7 Jan 05 2023 11:04:30 %S A359522 0,0,0,0,0,0,1,5,32,144,662,2835,11955,49083,199029,796867,3163384, %T A359522 12463807 %N A359522 Number of free, holey, treelike polyominoes of n cells. %e A359522 a(7) = 1 because of the holey heptomino. %Y A359522 Cf. A000105, A001419, A131482. %K A359522 nonn,more %O A359522 1,8 %A A359522 _John Mason_, Jan 04 2023