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A148163
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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), (0, 1, -1), (1, 0, 0)}
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0
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1, 1, 2, 4, 11, 31, 91, 283, 901, 2904, 9521, 31808, 107236, 364364, 1251636, 4333312, 15077986, 52788201, 185909398, 657386742, 2333476922, 8317496562, 29746811372, 106682779598, 383721471229, 1383920063898, 5002364671105, 18120720841491, 65780485710789, 239235254890321, 871545199855827, 3180392395993126
(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, j, k, -1 + n] + aux[i, -1 + 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: A148160 A148161 A148162 * A039300 A118974 A119020
Adjacent sequences: A148160 A148161 A148162 * A148164 A148165 A148166
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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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