%I A151445
%S A151445 1,1,2,6,16,49,165,538,1881,6673,23954,87931,326739,1224662,4649697,17778696,
               68513483,
%T A151445 265907818,1038089219,4074688736,16076107171,63703583554,253492204031,
               1012528480799,
%U A151445 4058431546038,16319598817463,65820404923113,266202737052052,1079421216584541,
               4387508855164279
%N A151445 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), (0, 1), (1, -1), (1, 0), (1, 1)}
%H A151445 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 A151445 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, 1 + j, -1 + 
               n]]; Table[Sum[aux[0, k, n], {k, 0, n}], {n, 0, 25}]
%Y A151445 Sequence in context: A079565 A052890 A052814 this_sequence A000136 A013989 
               A002841
%Y A151445 Adjacent sequences: A151442 A151443 A151444 this_sequence A151446 A151447 
               A151448
%K A151445 nonn,walk
%O A151445 0,3
%A A151445 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008