%I A150027
%S A150027 1,2,5,19,74,298,1281,5462,24099,108077,487391,2236789,10301023,47843041,
               223735126,1049895022,
%T A150027 4956915448,23474704967,111584020732,532185167879,2544210999914,12197908389471,
               58601743861377,
%U A150027 282127456392257,1360861827426384,6574796619320823,31817366089923143,154187495072008827
%N A150027 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, 0), (1, 0, 1), (1, 1, -1)}
%H A150027 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 A150027 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, 1 + k, -1 + n] + aux[-1 
               + i, j, -1 + k, -1 + n] + aux[i, -1 + j, 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 A150027 Sequence in context: A106873 A014273 A150026 this_sequence A058131 A138911 
               A107377
%Y A150027 Adjacent sequences: A150024 A150025 A150026 this_sequence A150028 A150029 
               A150030
%K A150027 nonn,walk
%O A150027 0,2
%A A150027 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008