%I A150568
%S A150568 1,2,7,26,107,462,2053,9357,43312,203180,962555,4596511,22091572,106733036,
               517927304,
%T A150568 2522423944,12322749650,60357919187,296304581671,1457419770252,7180626570463,
               35430558631116,
%U A150568 175046219852421,865804309015437,4286686560241754,21242694102354515,105351540746353992
%N A150568 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, 0, 1), (0, -1, 1), 
               (0, 1, -1), (1, 0, 0), (1, 1, 0)}
%H A150568 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 A150568 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, -1 + j, k, -1 + n] + aux[-1 + 
               i, j, k, -1 + n] + aux[i, -1 + j, 1 + k, -1 + n] + aux[i, 1 + j, 
               -1 + k, -1 + n] + aux[1 + i, j, -1 + k, -1 + n]]; Table[Sum[aux[i, 
               j, k, n], {i, 0, n}, {j, 0, n}, {k, 0, n}], {n, 0, 10}]
%Y A150568 Sequence in context: A150566 A150567 A000151 this_sequence A102319 A006603 
               A080244
%Y A150568 Adjacent sequences: A150565 A150566 A150567 this_sequence A150569 A150570 
               A150571
%K A150568 nonn,walk
%O A150568 0,2
%A A150568 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008