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Search: id:A151470
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| A151470 |
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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), (1, 0), (1, 1)} |
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+0
1
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| 1, 1, 6, 18, 94, 386, 1979, 9262, 47785, 238604, 1246969, 6454615, 34187874, 180940665, 969918088, 5211150923, 28218545331, 153283951381, 837083867878, 4585637886067, 25219366928380, 139092895929290, 769504571196682, 4267822299499544, 23729769950773771, 132230104921510603, 738390549104421575
(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] + 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: A121156 A057051 A104970 this_sequence A009573 A052655 A108735
Adjacent sequences: A151467 A151468 A151469 this_sequence A151471 A151472 A151473
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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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