A202816 The left-hand half-triangle of A185356 (or A202690).

1, 1, 0, 3, 4, 4, 11, 8, 4, 0, 57, 68, 76, 80, 80, 361, 304, 236, 160, 80, 0, 2763, 3124, 3428, 3664, 3824, 3904, 3904, 24611, 21848, 18724, 15296, 11632, 7808, 3904, 0, 250737, 275348, 297196, 315920, 331216, 342848, 350656, 354560, 354560

Offset: 1

Author

N. J. A. Sloane, Dec 25 2011

Keywords

• nonn
• tabl

Examples

			Triangle begins:
    1
    1   0
    3   4   4
   11   8   4   0
   57  68  76  80 80
  361 304 236 160 80 0
  ...
		

Links

• M. Josuat-Vergès, J.-C. Novelli and J.-Y. Thibon, The algebraic combinatorics of snakes, arXiv preprint arXiv:1110.5272 [math.CO], 2011.

Crossrefs

Cf. A185356, A202690, A202815.

Programs

PARI

T(n,k) = {if ((k==0), return(0)); if (n==1, if (abs(k)==1, return(1))); if (n%2, if (k<0, sum(j=k+1, n-1, T(n-1,j)), sum(j=k, n-1, T(n-1,j))), if (k<0, sum(j=-n+1, k, T(n-1,j)), sum(j=-n+1, k-1, T(n-1,j))));}
tabl(nn) = {for (n=1, nn, for (k=1, n, if (k, print1(T(n, -k), ", "));); print;);} \\ Michel Marcus, Jun 03 2020

Extensions

More terms from Michel Marcus, Jun 03 2020