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A151321
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Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 1), (0, 1), (1, -1), (1, 0), (1, 1)}
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0
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1, 3, 13, 59, 279, 1341, 6527, 31995, 157659, 779601, 3864985, 19197119, 95485691, 475450235, 2369357063, 11815028649, 58946549799, 294208885315, 1468899193277, 7335669719437, 36641882024645, 183058171254391, 914661462596977, 4570679817175993, 22842398781064325, 114165818614661101
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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LINKS
| M. Bousquet-Melou and M. Mishna, 2008. Walks with small steps in the quarter plane, ArXiv 0810.4387.
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, n_Integer] := Which[Min[i, j, n] < 0 || Max[i, j] > n, 0, n == 0, KroneckerDelta[i, j, n], True, aux[i, j, n] = aux[-1 + i, -1 + j, -1 + n] + aux[-1 + i, j, -1 + n] + aux[-1 + i, 1 + j, -1 + n] + aux[i, -1 + j, -1 + n] + aux[1 + i, -1 + j, -1 + n]]; Table[Sum[aux[i, j, n], {i, 0, n}, {j, 0, n}], {n, 0, 25}]
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CROSSREFS
| Sequence in context: A151229 A151230 A151231 * A151232 A151233 A151234
Adjacent sequences: A151318 A151319 A151320 * A151322 A151323 A151324
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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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