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 A151274 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, 0), (0, -1), (1, -1), (1, 1)} 0
 1, 1, 5, 13, 51, 179, 685, 2609, 10269, 40435, 162355, 654197, 2663021, 10896113, 44862303, 185524733, 770809891, 3213995231, 13449327811, 56449627333, 237606240991, 1002649516511, 4240932519555, 17976119289559, 76346766385593, 324842947451253, 1384493839712331, 5910024485652133 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS M. Bousquet-MÃ©lou 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, 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[i, j, n], {i, 0, n}, {j, 0, n}], {n, 0, 25}] CROSSREFS Sequence in context: A146657 A243304 A238508 * A149538 A149539 A007231 Adjacent sequences:  A151271 A151272 A151273 * A151275 A151276 A151277 KEYWORD nonn,walk AUTHOR Manuel Kauers, Nov 18 2008 STATUS approved

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Last modified March 21 04:59 EDT 2019. Contains 321364 sequences. (Running on oeis4.)