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Search: id:A151430
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| A151430 |
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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), (0, 1), (1, -1), (1, 0)} |
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+0
1
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| 1, 1, 2, 7, 19, 61, 224, 771, 2855, 11005, 41963, 165661, 664443, 2674101, 10955892, 45281419, 188288455, 790957165, 3343062477, 14209485769, 60792612875, 261330644741, 1128597807923, 4896682653677, 21327006074731, 93233880458581, 409028951228459, 1800105977084221, 7946053746358811
(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[-1 + i, 1 + j, -1 + n] + aux[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: A030224 A114624 A091024 this_sequence A083309 A164979 A080873
Adjacent sequences: A151427 A151428 A151429 this_sequence A151431 A151432 A151433
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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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