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 A137334 #5 Apr 07 2020 23:35:19 %S A137334 1,2,10,45,302,3102,45795 %N A137334 Number of n X n crossword puzzles with dihedral symmetry group, for n odd. Acceptable crossword puzzles must have all words of length 3 or more, at least one word in each row and each column and be connected. %C A137334 The number of such puzzles for an even n = 2m is equal to the number of (2m-1) X (2m-1) puzzles. %H A137334 Marc Brodie, <a href="/A137334/a137334.txt">Mathematica program</a> %e A137334 a(5) = 2 because, using 0's for white squares and 1's for black squares, the only two 5 X 5 puzzles with dihedral symmetry group are: %e A137334 00000 %e A137334 00000 %e A137334 00000 %e A137334 00000 %e A137334 00000 %e A137334 and %e A137334 10001 %e A137334 00000 %e A137334 00000 %e A137334 00000 %e A137334 10001 %Y A137334 Cf. A130578, A133226, A133253, A133258. %K A137334 nonn %O A137334 3,2 %A A137334 Marc Brodie (mbrodie(AT)wju.edu), Apr 07 2008