%I A151131
%S A151131 1,3,11,45,198,882,4006,18505,86473,406981,1928110,9185789,43958967,211147220,
               1017380648,
%T A151131 4915403582,23804986783,115526616241,561669161351,2735112582225,13338235034978,
               65130900798744,
%U A151131 318406433843562,1558239000906143,7633165587296164,37424723726355602,183638260399843749
%N A151131 Number of walks within N^3 (the first octant of Z^3) starting at (0,0,
               0) and consisting of n steps taken from {(-1, -1, 0), (0, 0, -1), 
               (0, 1, 0), (0, 1, 1), (1, 0, 1)}
%H A151131 A. Bostan and M. Kauers, 2008. Automatic Classification of Restricted 
               Lattice Walks, <a href="http://arxiv.org/abs/0811.2899">ArXiv 0811.2899</
               a>.
%t A151131 aux[i_Integer, j_Integer, k_Integer, n_Integer] := Which[Min[i, j, k, 
               n] < 0 || Max[i, j, k] > n, 0, n == 0, KroneckerDelta[i, j, k, n], 
               True, aux[i, j, k, n] = aux[-1 + i, j, -1 + k, -1 + n] + aux[i, -1 
               + j, -1 + k, -1 + n] + aux[i, -1 + j, k, -1 + n] + aux[i, j, 1 + 
               k, -1 + n] + aux[1 + i, 1 + j, k, -1 + n]]; Table[Sum[aux[i, j, k, 
               n], {i, 0, n}, {j, 0, n}, {k, 0, n}], {n, 0, 10}]
%Y A151131 Sequence in context: A049177 A080243 A001003 this_sequence A151132 A151133 
               A083886
%Y A151131 Adjacent sequences: A151128 A151129 A151130 this_sequence A151132 A151133 
               A151134
%K A151131 nonn,walk
%O A151131 0,2
%A A151131 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008