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Search: id:A151449
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| A151449 |
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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, 0), (-1, 1), (0, -1), (1, -1), (1, 1)} |
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+0
1
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| 1, 0, 2, 4, 18, 46, 214, 742, 3146, 12162, 51862, 214090, 921302, 3937074, 17192430, 75188002, 332778382, 1478794218, 6622770990, 29791504178, 134763557054, 612115880722, 2792465318950, 12785429645706, 58747776081670, 270792162028674, 1251949437110774, 5804003443798442, 26976870402858422
(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, -1 + j, -1 + n] + aux[-1 + i, 1 + j, -1 + n] + aux[i, 1 + j, -1 + n] + aux[1 + i, -1 + j, -1 + n] + aux[1 + i, 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: A063101 A143533 A064723 this_sequence A045664 A106520 A093045
Adjacent sequences: A151446 A151447 A151448 this_sequence A151450 A151451 A151452
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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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