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 A366399 #16 Oct 09 2023 14:00:52 %S A366399 1,1,4,1,8,20,1,14,62,276,1,22,132,1006,4324,1,32,336,3610,26996, %T A366399 229348,1,44,688,12010,109722,1620034,13535280,1,58,1578,38984,602804, %U A366399 12071462,175905310,3023313284,1,74,3190,122188,2434670,82550864,1449655468,43551685370,745416341496 %N A366399 Triangle read by rows: T(n,k) is the number of paths traveling orthogonally on an n X k grid that visit every cell. %e A366399 T(n,k) is a triangular array read by rows: %e A366399 1, %e A366399 1, 4, %e A366399 1, 8, 20, %e A366399 1, 14, 62, 276, %e A366399 ... %e A366399 T(2,2) = 4: %e A366399 +---+---+ +---+---+ +---+---+ +---+---+ %e A366399 | | | | | | | | | | | | %e A366399 | **|** | | * | * | | **|** | | **|** | %e A366399 | | * | | * | * | | * | | | * | * | %e A366399 +---+---+ +---+---+ +---+---+ +---+---+ %e A366399 | | * | | * | * | | * | | | * | * | %e A366399 | **|** | | **|** | | **|** | | * | * | %e A366399 | | | | | | | | | | | | %e A366399 +---+---+ +---+---+ +---+---+ +---+---+ %Y A366399 See A332307 for another version. %Y A366399 Cf. A120443 (T(n,n)), A366411 (row sums). %K A366399 tabl,nonn,walk %O A366399 1,3 %A A366399 _Douglas Boffey_, Oct 09 2023 %E A366399 More terms (using A332307) from _Pontus von Brömssen_, Oct 09 2023