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A150117 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, 1, 1), (0, 0, 1), (0, 1, 1), (1, 0, -1)} 0
1, 2, 6, 19, 71, 266, 1067, 4305, 18014, 75777, 325681, 1406093, 6155189, 27052449, 120016165, 534302674, 2394568143, 10764279292, 48627361446, 220252330255, 1001372358051, 4563155984765, 20855602666094, 95509597943726, 438440956658340, 2016199473552408, 9289959447386694, 42870670999074681 (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, 1 + 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] + 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: A150115 A177477 A150116 * A038392 A044045 A150118

Adjacent sequences:  A150114 A150115 A150116 * A150118 A150119 A150120

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified October 13 23:58 EDT 2019. Contains 327986 sequences. (Running on oeis4.)