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Search: id:A151355
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| A151355 |
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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), (1, 1)} |
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+0
1
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| 1, 0, 1, 2, 4, 14, 45, 120, 468, 1478, 5208, 18714, 67200, 244208, 914953, 3393606, 12865732, 48963934, 187738332, 724740954, 2816697570, 10990919138, 43152034764, 170075450764, 673260699676, 2675316693314, 10669114073080, 42685090123056, 171316969097872, 689506156453890, 2782631094476893
(list; graph; listen)
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OFFSET
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0,4
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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[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
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Sequence in context: A047152 A007866 A121751 this_sequence A014272 A070822 A101536
Adjacent sequences: A151352 A151353 A151354 this_sequence A151356 A151357 A151358
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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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