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A149615 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), (0, 1, -1), (1, 1, 1)} 0
1, 1, 5, 15, 63, 243, 1019, 4273, 18309, 79537, 347953, 1540517, 6848389, 30699769, 138103437, 624792087, 2835583031, 12920696755, 59038536867, 270570671015, 1242960486199, 5723341739351, 26406806760755, 122069901607203, 565252421469507, 2621600015540423, 12176517064331299, 56632633782716711 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

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, -1 + k, -1 + n] + aux[i, -1 + 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: A149612 A149613 A149614 * A149616 A189945 A066886

Adjacent sequences:  A149612 A149613 A149614 * A149616 A149617 A149618

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified October 15 20:06 EDT 2021. Contains 348034 sequences. (Running on oeis4.)