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A148132 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, 0, -1), (0, 1, 0), (1, -1, 0)} 0
1, 1, 2, 4, 11, 28, 77, 228, 692, 2160, 6879, 22528, 75430, 254868, 875874, 3055683, 10765198, 38352888, 137848862, 499998280, 1829241456, 6733795838, 24970420936, 93195229701, 349695790406, 1319823920870, 5005256608864, 19072570922847, 73017219637011, 280622498877470, 1082966473242941, 4195021392215434 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Table of n, a(n) for n=0..31.

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[i, -1 + j, k, -1 + n] + aux[i, 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: A026122 A108629 A007048 * A032101 A005200 A148133

Adjacent sequences:  A148129 A148130 A148131 * A148133 A148134 A148135

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified October 22 01:42 EDT 2018. Contains 316431 sequences. (Running on oeis4.)