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A151349
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Number of walks within N^2 (the first quadrant of Z^2) starting and ending at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, -1)}
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0
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1, 0, 1, 1, 5, 8, 40, 91, 406, 1167, 4956, 16349, 68312, 246502, 1027322, 3938800, 16499271, 65979431, 278832735, 1149369374, 4907324239, 20691994829, 89274013063, 383084876832, 1669457571727, 7264787659538, 31956494188222, 140668018518295, 624084995417305, 2773778482274832
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,5
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LINKS
| M. Bousquet-Melou and M. Mishna, 2008. Walks with small steps in the quarter plane, ArXiv 0810.4387.
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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[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[aux[0, 0, n], {n, 0, 25}]
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CROSSREFS
| Sequence in context: A075273 A176859 A176757 * A192272 A073930 A130223
Adjacent sequences: A151346 A151347 A151348 * A151350 A151351 A151352
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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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