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Search: id:A151464
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| A151464 |
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Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0), ending on the vertical axis and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, 0)} |
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+0
1
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| 1, 1, 4, 12, 46, 180, 745, 3185, 14000, 62832, 287154, 1331484, 6251916, 29671356, 142132848, 686420592, 3338939032, 16345771728, 80480627656, 398307700648, 1980504505408, 9889617286848, 49575852422122, 249406833948012, 1258841279547604, 6373077654620340, 32355358786303440, 164693131263424560
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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M. Bouquet-Melou and M. Mishna, 2008. Walks with small steps in the quarter plane, ArXiv 0810.4387.
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MATHEMATICA
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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, j, -1 + n] + aux[i, -1 + j, -1 + n] + aux[i, 1 + j, -1 + n] + aux[1 + i, -1 + j, -1 + n] + aux[1 + i, j, -1 + n] + aux[1 + i, 1 + j, -1 + n]]; Table[Sum[aux[0, k, n], {k, 0, n}], {n, 0, 25}]
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CROSSREFS
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Sequence in context: A149372 A126202 A149373 this_sequence A101225 A000775 A149374
Adjacent sequences: A151461 A151462 A151463 this_sequence A151465 A151466 A151467
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KEYWORD
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nonn,walk
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AUTHOR
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Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008
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