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A150088 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, 0, 1), (0, 1, 0), (1, -1, -1), (1, 1, 0)} 0
1, 2, 6, 19, 66, 243, 930, 3676, 14903, 61584, 258894, 1103447, 4758012, 20732432, 91124592, 403681327, 1800752730, 8081803201, 36474901389, 165435268106, 753751636931, 3448465225387, 15836193654948, 72977234653985, 337370456592555, 1564255503416559, 7272766119061584, 33899558103994633 (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, -1 + j, k, -1 + n] + aux[-1 + i, 1 + j, 1 + k, -1 + n] + aux[i, -1 + j, k, -1 + n] + aux[1 + i, 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}]

CROSSREFS

Sequence in context: A005654 A150086 A150087 * A150089 A150090 A150091

Adjacent sequences:  A150085 A150086 A150087 * A150089 A150090 A150091

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified October 15 16:30 EDT 2018. Contains 316236 sequences. (Running on oeis4.)