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 A342538 #10 Mar 24 2021 23:07:44 %S A342538 1,0,1,2,4,7,17,40,101,259,671,1741,4689,12511,33603,91249 %N A342538 Number of free polyominoes with n cells having simply-connected interiors such that no smaller polyomino has the same bracelet. %C A342538 Consider only the corners of the polygon that forms the border of the polyomino. Then build the bracelet of black and white beads by following the border of the polygon in a clockwise direction, adding a black bead for each right-turning right angle, and a white bead for each left-turning right angle. Count in this sequence only polyominoes for which no smaller polyomino has the same bracelet. Note 2 polyominoes of the same size having the same bracelet will count as 2. %e A342538 a(2) is 0 as the domino has bracelet BBBB, which is the same as the monomino. %Y A342538 Cf. A342537. %K A342538 nonn,more %O A342538 1,4 %A A342538 _John Mason_, _Allan C. Wechsler_, Mar 15 2021