

A150850


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, 0), (0, 1, 1), (1, 0, 1), (1, 0, 0), (1, 1, 1)}


0



1, 2, 8, 32, 140, 624, 2835, 13083, 60972, 286915, 1358879, 6471544, 30958497, 148639296, 715975304, 3458054422, 16742032860, 81223525103, 394774557700, 1921859283853, 9369609275641, 45739130217128, 223544562299062, 1093714600090306, 5356310718357100, 26255094806635557, 128799993599104739
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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, k, 1 + n] + aux[1 + i, j, 1 + k, 1 + n] + aux[i, 1 + j, 1 + k, 1 + n] + aux[1 + i, j, 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: A150847 A150848 A150849 * A179469 A150851 A150852
Adjacent sequences: A150847 A150848 A150849 * A150851 A150852 A150853


KEYWORD

nonn,walk


AUTHOR

Manuel Kauers, Nov 18 2008


STATUS

approved



