%I A148161
%S A148161 1,1,2,4,11,31,86,262,787,2442,7677,24581,80379,261809,867313,2890472,
               9684442,32683354,
%T A148161 110898717,379064856,1297810439,4466393711,15433476163,53483388756,185962286216,
               648576840593,
%U A148161 2269821822857,7957275602226,27969780462858,98546712605786,347890004162970,
               1230552458589243
%N A148161 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), (-1, 1, 1), 
               (0, 1, -1), (1, 0, 0)}
%H A148161 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 A148161 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, k, -1 + n] + aux[i, -1 + j, 
               1 + k, -1 + n] + aux[1 + i, -1 + 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 A148161 Sequence in context: A034770 A002387 A148160 this_sequence A148162 A148163 
               A039300
%Y A148161 Adjacent sequences: A148158 A148159 A148160 this_sequence A148162 A148163 
               A148164
%K A148161 nonn,walk
%O A148161 0,3
%A A148161 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008