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A148877
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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, 1, 1), (1, 0, 1), (1, 1, -1)}
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0
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1, 1, 3, 8, 30, 93, 359, 1209, 4730, 16655, 65691, 237665, 941630, 3468116, 13778724, 51387436, 204534160, 769868698, 3068092161, 11630032273, 46389072310, 176824017758, 705754225977, 2702266273070, 10790600421380, 41469337360702, 165652900932831, 638598964506103, 2551632767608252
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,3
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LINKS
| A. Bostan and M. Kauers, 2008. Automatic Classification of Restricted Lattice Walks, ArXiv 0811.2899.
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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, -1 + 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}]
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CROSSREFS
| Sequence in context: A130470 A162054 A067354 * A148878 A148879 A148880
Adjacent sequences: A148874 A148875 A148876 * A148878 A148879 A148880
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KEYWORD
| nonn,walk
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AUTHOR
| Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008
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