cp's OEIS Frontend

A358996 Number of self-avoiding paths of length 2*(n+A002620(n-1)) along the edges of a grid with n X n square cells, which do not pass above the diagonal, start at the lower left corner and finish at the upper right corner.

%I A358996 #14 Dec 09 2022 16:05:13
%S A358996 1,1,2,2,10,20,248,1072,31178,270026,18806964,329412610,54393195014,
%T A358996 1931171930256,749416883107560,54217060622200086
%N A358996 Number of self-avoiding paths of length 2*(n+A002620(n-1)) along the edges of a grid with n X n square cells, which do not pass above the diagonal, start at the lower left corner and finish at the upper right corner.
%F A358996 a(n) = A340043(n, A002620(n-1)).
%e A358996 3 X 3 square cells
%e A358996   *---*---*---E
%e A358996   |   |   |   |
%e A358996   *---*---*---*
%e A358996   |   |   |   |
%e A358996   *---*---*---*
%e A358996   |   |   |   |
%e A358996   S---*---*---*
%e A358996 a(3) = 2;
%e A358996               E              E
%e A358996               |              |
%e A358996               *          *---*
%e A358996               |          |
%e A358996       *---*   *          *---*
%e A358996       |   |   |              |
%e A358996   S---*   *---*  S---*---*---*
%Y A358996 Cf. A000108, A002620, A340005, A340043.
%K A358996 nonn,more
%O A358996 0,3
%A A358996 _Seiichi Manyama_, Dec 09 2022