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A151322 Number of walks within N^2 (the first quadrant of Z^2) starting at (0,0) and consisting of n steps taken from {(-1, -1), (-1, 1), (-1, 0), (0, 1), (1, 0), (1, 1)} 0
1, 3, 14, 65, 330, 1683, 8874, 47088, 253802, 1375939, 7524651, 41346061, 228447273, 1267005772, 7054307476, 39394861448, 220641191059, 1238773724011, 6970910527593, 39305772011050, 222039381179593, 1256404002028860, 7120347445063067, 40409910873522737, 229639109317630051, 1306567259328079561 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..25.

M. Bousquet-Mélou 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[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[i, j, n], {i, 0, n}, {j, 0, n}], {n, 0, 25}]

CROSSREFS

Sequence in context: A026592 A034275 A240008 * A002320 A151323 A181662

Adjacent sequences:  A151319 A151320 A151321 * A151323 A151324 A151325

KEYWORD

nonn,walk

AUTHOR

Manuel Kauers, Nov 18 2008

STATUS

approved

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Last modified July 12 06:48 EDT 2020. Contains 335657 sequences. (Running on oeis4.)