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A149942 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), (0, 0, -1), (0, 1, -1), (1, 0, 0), (1, 1, 0)} 0
1, 2, 5, 15, 49, 172, 627, 2364, 9178, 36322, 146349, 598798, 2479100, 10377197, 43854651, 186810219, 801663799, 3462831008, 15043186516, 65697663852, 288296368358, 1270513998501, 5621498699217, 24963796571708, 111226042313882, 497111195713677, 2228180310648286, 10013702555716602 (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, j, k, -1 + n] + aux[i, -1 + j, 1 + k, -1 + n] + aux[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: A149939 A149940 A149941 * A149943 A079146 A000734

Adjacent sequences:  A149939 A149940 A149941 * A149943 A149944 A149945

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified April 10 02:20 EDT 2020. Contains 333392 sequences. (Running on oeis4.)