%I A151496
%S A151496 1,1,7,27,160,870,5345,32865,211512,1380372,9214548,62327958,427516056,
               2963478804,20745401391,
%T A151496 146427786219,1041261685464,7453015732448,53661092431232,388397497629284,
               2824677704718896,
%U A151496 20632192727484936,151301370605585252,1113568687159297278,8223216946375477960
%N A151496 Number of walks within N^2 (the first quadrant of Z^2) starting at (0,
               0), ending on the vertical axis and consisting of n steps taken from 
               {(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, -1), (1, 0), (1, 
               1)}
%H A151496 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 A151496 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[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[0, k, n], {k, 0, n}], {n, 0, 25}]
%Y A151496 Sequence in context: A118101 A147996 A034536 this_sequence A035081 A003148 
               A033910
%Y A151496 Adjacent sequences: A151493 A151494 A151495 this_sequence A151497 A151498 
               A151499
%K A151496 nonn,walk
%O A151496 0,3
%A A151496 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008