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A151028 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, 0, 1), (-1, 1, 1), (1, 0, -1), (1, 0, 1), (1, 1, 1)} 0
1, 2, 10, 40, 200, 888, 4440, 20640, 103200, 491072, 2455360, 11842560, 59212800, 288052864, 1440264320, 7047424000, 35237120000, 173139514368, 865697571840, 4266803935232, 21334019676160, 105398337126400, 526991685632000, 2608355721134080, 13041778605670400, 64645756083503104, 323228780417515520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..26.

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, j, 1 + k, -1 + n] + aux[1 + i, -1 + j, -1 + k, -1 + n] + aux[1 + i, 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: A151026 A151027 A188325 * A282619 A080252 A318694

Adjacent sequences:  A151025 A151026 A151027 * A151029 A151030 A151031

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified October 21 05:02 EDT 2019. Contains 328291 sequences. (Running on oeis4.)