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A202816
The left-hand half-triangle of A185356 (or A202690).
2
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
1,4
LINKS
M. Josuat-Vergès, J.-C. Novelli and J.-Y. Thibon, The algebraic combinatorics of snakes, arXiv preprint arXiv:1110.5272 [math.CO], 2011.
EXAMPLE
Triangle begins:
1
1 0
3 4 4
11 8 4 0
57 68 76 80 80
361 304 236 160 80 0
...
PROG
(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
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
N. J. A. Sloane, Dec 25 2011
EXTENSIONS
More terms from Michel Marcus, Jun 03 2020
STATUS
approved