A202690 The triangle in A185356 with the central column of zeros omitted.

1, 1, 0, 1, 1, 2, 4, 4, 3, 3, 2, 0, 0, 4, 8, 11, 11, 14, 16, 16, 80, 80, 76, 68, 57, 57, 46, 32, 16, 0, 0, 80, 160, 236, 304, 361, 361, 418, 464, 496, 512, 512, 3904, 3904, 3824, 3664, 3428, 3124, 2763, 2763, 2402, 1984, 1520, 1024, 512, 0

Offset

1,6

Links

Table of n, a(n) for n=1..56.

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   1 1   2
             4   4   3 3   2   0
         0   4   8  11 11  14  16  16
    80  80  76  68  57 57  46  32  16  0
  0 80 160 236 304 361 361 418 464 496 512 512

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)))); }
tabf(nn) = {for (n=1, nn, for (k=-n, n, if (k, print1(T(n, k), ", ")); ); print; ); } \\ Michel Marcus, Jun 03 2020

Crossrefs

Cf. A185356, A202691, A202704.

Sequence in context: A306691 A354954 A237496 * A342754 A257978 A193358

Adjacent sequences: A202687 A202688 A202689 * A202691 A202692 A202693

Keyword

nonn,tabf

Author

N. J. A. Sloane, Dec 22 2011

Extensions

More terms from Michel Marcus, Jun 03 2020

Status

approved