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 A215874 #7 Jul 24 2025 19:39:42 %S A215874 1,1,1,8,50,1233,15485,767560,14296434,1124811332 %N A215874 Number of permutations of 0..floor((6*n-2)/2) on odd squares of an 6Xn array such that each row, column, diagonal and (downwards) antidiagonal of odd squares is increasing. %C A215874 Row 6 of A215870 %e A215874 Some solutions for n=4 %e A215874 ..x..0..x..2....x..0..x..1....x..0..x..1....x..0..x..1....x..0..x..2 %e A215874 ..1..x..3..x....2..x..3..x....2..x..3..x....2..x..3..x....1..x..3..x %e A215874 ..x..4..x..5....x..4..x..6....x..4..x..5....x..4..x..5....x..4..x..6 %e A215874 ..6..x..7..x....5..x..7..x....6..x..7..x....6..x..7..x....5..x..7..x %e A215874 ..x..8..x.10....x..8..x.10....x..8..x..9....x..8..x.10....x..8..x..9 %e A215874 ..9..x.11..x....9..x.11..x...10..x.11..x....9..x.11..x...10..x.11..x %K A215874 nonn %O A215874 1,4 %A A215874 _R. H. Hardin_ Aug 25 2012