%I A151347
%S A151347 1,0,1,1,3,8,19,65,177,611,1928,6648,22928,80851,292343,1063611,3957406,
               14818681,56339994,
%T A151347 215943994,836246604,3265240671,12848804154,50936668789,203235590343,816070826188,
%U A151347 3295317218038,13379003847708,54588942258042,223782828113783,921414594957514,
               3809576782931810
%N A151347 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, 0), (-1, 1), 
               (0, -1), (0, 1), (1, -1)}
%H A151347 M. Bouquet-Melou and M. Mishna, 2008. Walks with small steps in the quarter 
               plane, <a href="http://arxiv.org/abs/0810.4387">ArXiv 0810.4387</
               a>.
%t A151347 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[i, 1 + 
               j, -1 + n] + aux[1 + i, -1 + j, -1 + n] + aux[1 + i, j, -1 + n]]; 
               Table[aux[0, 0, n], {n, 0, 25}]
%Y A151347 Sequence in context: A164586 A018032 A086808 this_sequence A047093 A060305 
               A009141
%Y A151347 Adjacent sequences: A151344 A151345 A151346 this_sequence A151348 A151349 
               A151350
%K A151347 nonn,walk
%O A151347 0,5
%A A151347 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008