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 A132444 #2 Feb 27 2009 03:00:00 %S A132444 0,0,0,1,1,5,6,60,93 %N A132444 Number of n x n crossword puzzles with rotational symmetry and exactly one black square per row, up to symmetry. %C A132444 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. Since the puzzles counted in sequence A132443 come naturally in pairs (by reflective symmetry), the numbers in this sequence are obtained by dividing the corresponding numbers in A132443 by 2. %e A132444 a(6) = 1 because up to symmetry, the only 6 X 6 crossword puzzle with exactly one black square in each row (using 1's for black squares and 0's for white) is: %e A132444 100000 %e A132444 100000 %e A132444 100000 %e A132444 000001 %e A132444 000001 %e A132444 000001 %p A132444 See the program for A132443 %Y A132444 Cf. A130578, A132443, A132445, A132446. %K A132444 nonn %O A132444 3,6 %A A132444 Marc Brodie (mbrodie(AT)wju.edu), Aug 21 2007