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Search: id:A151450
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| A151450 |
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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, 0), (1, 1)} |
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+0
1
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| 1, 0, 4, 5, 34, 98, 458, 1703, 7632, 31222, 139078, 601834, 2692054, 12000298, 54304846, 246205555, 1126480236, 5170553126, 23870651114, 110597543652, 514517316974, 2401300629466, 11243551419878, 52789725198754, 248514184071046, 1172682575616138, 5545963779654358, 26282130844530698
(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, 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: A128867 A013468 A041907 this_sequence A131139 A152291 A041557
Adjacent sequences: A151447 A151448 A151449 this_sequence A151451 A151452 A151453
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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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