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A151320 Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, 0), (0, 1), (1, -1), (1, 0), (1, 1)} +0
1
1, 3, 13, 58, 270, 1280, 6150, 29805, 145360, 712206, 3501803, 17264747, 85302729, 422197260, 2092558843, 10383452493, 51573082768, 256362474771, 1275210602985, 6346900307554, 31605149836728, 157449319326981, 784667701737738, 3911759095866487, 19506630908252765, 97297440023869383 (list; graph; listen)
OFFSET

0,2

LINKS

M. Bouquet-Melou and M. Mishna, 2008. Walks with small steps in the quarter plane, ArXiv 0810.4387.

A. Bostan and M. Kauers, 2008. Automatic Classification of Restricted Lattice Walks, ArXiv 0811.2899.

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[-1 + i, j, -1 + n] + aux[-1 + i, 1 + j, -1 + n] + aux[i, -1 + j, -1 + n] + aux[1 + i, j, -1 + n]]; Table[Sum[aux[i, j, n], {i, 0, n}, {j, 0, n}], {n, 0, 25}]

CROSSREFS

Sequence in context: A151224 A151225 A151226 this_sequence A151227 A151228 A152594

Adjacent sequences: A151317 A151318 A151319 this_sequence A151321 A151322 A151323

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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