

A150847


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


0



1, 2, 8, 32, 140, 617, 2825, 12989, 60799, 285605, 1355212, 6448778, 30876524, 148182226, 714046275, 3447484841, 16691884243, 80949584877, 393388278159, 1914344878230, 9330462585841, 45528694065925, 222436937930322, 1087807926738612, 5325191050098931, 26090385582013999, 127934831995426037
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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, 1 + k, 1 + n] + aux[i, 1 + j, 1 + k, 1 + n] + aux[1 + i, 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: A151828 A150845 A150846 * A150848 A150849 A150850
Adjacent sequences: A150844 A150845 A150846 * A150848 A150849 A150850


KEYWORD

nonn,walk


AUTHOR

Manuel Kauers, Nov 18 2008


STATUS

approved



