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Revision History for A149951 (Bold, blue-underlined text is an addition; faded, red-underlined text is a deletion.)

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Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, -1, 1), (0, 0, 1), (0, 1, 0), (1, 1, -1)}
(history; published version)
#2 by Russ Cox at Fri Mar 30 18:54:16 EDT 2012
AUTHOR

_Manuel Kauers (manuel(AT)kauers.de), _, Nov 18 2008

Discussion
Fri Mar 30
18:54
OEIS Server: https://oeis.org/edit/global/269
#1 by N. J. A. Sloane at Fri Jan 09 03:00:00 EST 2009
NAME

Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, -1, 1), (0, 0, 1), (0, 1, 0), (1, 1, -1)}

DATA

1, 2, 5, 15, 50, 176, 646, 2452, 9549, 37961, 153511, 629732, 2614885, 10972374, 46463260, 198334111, 852639288, 3688754625, 16049389276, 70187680379, 308375520541, 1360617913209, 6026613738270, 26788857783196, 119469665596501, 534412213485831, 2397257900073820, 10781700156879226

OFFSET

0,2

LINKS

A. Bostan and M. Kauers, 2008. Automatic Classification of Restricted Lattice Walks, <a href="http://arxiv.org/abs/0811.2899">ArXiv 0811.2899</a>.

MATHEMATICA

aux[i_Integer, j_Integer, k_Integer, n_Integer] := Which[Min[i, j, k, n] < 0 || Max[i, j, k] > n, 0, n == 0, KroneckerDelta[i, j, k, n], True, aux[i, j, k, n] = aux[-1 + i, -1 + j, 1 + k, -1 + n] + aux[i, -1 + j, k, -1 + n] + aux[i, j, -1 + k, -1 + n] + aux[1 + i, 1 + j, -1 + k, -1 + n] + aux[1 + i, 1 + j, k, -1 + n]]; Table[Sum[aux[i, j, k, n], {i, 0, n}, {j, 0, n}, {k, 0, n}], {n, 0, 10}]

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008

STATUS

approved