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A149017 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, 1), (1, -1, 1), (1, 0, 1), (1, 1, -1)} 0
1, 1, 3, 9, 35, 124, 510, 1996, 8486, 35018, 152208, 648852, 2864100, 12477480, 55706440, 246442952, 1109909256, 4966324677, 22522279875, 101658778771, 463622222653, 2107092862481, 9654437859981, 44122523527414, 202959384558304, 931821123572725, 4300695608582175, 19821228913467964 (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[-1 + i, j, -1 + k, -1 + n] + aux[-1 + i, 1 + j, -1 + k, -1 + n] + aux[1 + i, j, -1 + 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: A149015 A151452 A149016 * A149018 A149019 A102865

Adjacent sequences:  A149014 A149015 A149016 * A149018 A149019 A149020

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified June 13 05:21 EDT 2021. Contains 344981 sequences. (Running on oeis4.)