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 A188980 #6 Apr 02 2025 22:17:58 %S A188980 13,71865,577290185,2184414516364,9298230791255360 %N A188980 Number of n X 6 array permutations with each element moved but moved no more than a city block distance of two. %C A188980 Column 6 of A188981. %e A188980 Some solutions for 3 X 6 %e A188980 ..1..0..3..9.10.17....1..0..3.15.10.11....1..0..3..4..9.11....1..0..3.10..9.17 %e A188980 ..8..2.14..4.11.16....8..2..6..7.16..4....8..2..6..7..5.10....8..2.14.15.16..4 %e A188980 ..7..6.12.13.15..5...14.12.13..9.17..5...13.12.15.14.17.16....6..7.12.13.11..5 %Y A188980 Cf. A188981. %K A188980 nonn %O A188980 1,1 %A A188980 _R. H. Hardin_, Apr 14 2011