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A150245 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, 1), (-1, 0, 0), (0, 1, 1), (1, 0, -1), (1, 0, 0)} 0
1, 2, 6, 22, 84, 342, 1444, 6190, 27257, 121392, 547622, 2497948, 11472385, 53116882, 247297901, 1157377507, 5442548993, 25689616344, 121709902926, 578407050288, 2756553215354, 13171153867424, 63075808919137, 302708393573943, 1455496331745296, 7010622936173288, 33822329946221428, 163414315137681335 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..27.

A. Bostan and M. Kauers, 2008. Automatic Classification of Restricted Lattice Walks, ArXiv 0811.2899.

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, j, k, -1 + n] + aux[-1 + i, j, 1 + k, -1 + n] + aux[i, -1 + j, -1 + k, -1 + n] + aux[1 + i, j, k, -1 + n] + aux[1 + i, 1 + j, -1 + k, -1 + n]]; Table[Sum[aux[i, j, k, n], {i, 0, n}, {j, 0, n}, {k, 0, n}], {n, 0, 10}]

CROSSREFS

Sequence in context: A128723 A150244 A151288 * A150246 A055700 A150247

Adjacent sequences:  A150242 A150243 A150244 * A150246 A150247 A150248

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified November 23 13:52 EST 2014. Contains 249851 sequences.