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 A359068 #40 Jan 18 2023 03:25:16 %S A359068 1,1,2,5,10,24,52,124,282,668,1548,3654,8533,20093,47033,110533, %T A359068 258807,607227,1421055,3329585,7785995,18221563,42575336,99539106, %U A359068 232398659,542864111,1266567155,2956342341,6893180336,16078817198,37469245219,87347384305,203447081205 %N A359068 Number of 1-sided strip polyominoes with n cells. %C A359068 A "strip" polyomino is a snake polyomino (A151514) with no holes. %C A359068 This sequence first differs from A151514 at n = 7. An example of a polyomino counted by A151514, but not by this sequence, is: %C A359068 ### %C A359068 # # %C A359068 ## %H A359068 Arthur O'Dwyer, <a href="https://quuxplusone.github.io/blog/2022/12/08/polyomino-snakes/">Polyomino strips, snakes, and ouroboroi</a> (gives first 33 terms). %H A359068 Arthur O'Dwyer, <a href="https://quuxplusone.github.io/blog/code/2022-12-08-polyomino-snakes-and-strips.cpp">C++ program</a>. %o A359068 (C++) // see Links section %Y A359068 A333313 gives the number of free (2-sided) strip polyominoes with n cells. Subtracting A333313 from A359068 gives the number of chiral pairs. %Y A359068 A151514 gives the number of 1-sided snake polyominoes with n cells; A151514(n) > A359068(n) for n >= 7. %Y A359068 Subtracting A359068 from A151514 gives the number of snake polyominoes with n cells that have at least one hole. %K A359068 nonn,more %O A359068 1,3 %A A359068 _Arthur O'Dwyer_, Jan 11 2023