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A150254 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, 1, 0), (1, 0, -1), (1, 0, 1)} 0
1, 2, 6, 22, 85, 349, 1468, 6302, 27704, 123340, 556184, 2532801, 11624413, 53751684, 249963668, 1168605027, 5488578815, 25879275290, 122468470869, 581379728926, 2767823636347, 13211118238327, 63204241814159, 303027096900854, 1455646469490788, 7004908259344667, 33764527779636485, 162994289095084095 (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[-1 + i, j, 1 + k, -1 + n] + aux[i, -1 + j, 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: A150251 A150252 A150253 * A148497 A206736 A079105

Adjacent sequences:  A150251 A150252 A150253 * A150255 A150256 A150257

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified August 19 20:38 EDT 2022. Contains 356231 sequences. (Running on oeis4.)