%I A149424
%S A149424 1,1,4,13,40,136,496,1753,6256,22912,85216,314836,1170688,4396048,16623328,
               62744017,237680992,
%T A149424 904962400,3459831424,13219219972,50621972224,194465172304,749061374848,
               2884682636764,
%U A149424 11126422372864,43007603099296,166555051934848,644984620465264,2500560314630656
%N A149424 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, 0), (0, -1, 0), 
               (0, 0, -1), (1, 1, 1)}
%H A149424 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 A149424 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[i, 
               j, 1 + k, -1 + n] + aux[i, 1 + j, k, -1 + n] + aux[1 + i, j, k, -1 
               + n]]; Table[Sum[aux[i, j, k, n], {i, 0, n}, {j, 0, n}, {k, 0, n}], 
               {n, 0, 10}]
%Y A149424 Sequence in context: A098183 A094628 A034742 this_sequence A097112 A077284 
               A070428
%Y A149424 Adjacent sequences: A149421 A149422 A149423 this_sequence A149425 A149426 
               A149427
%K A149424 nonn,walk
%O A149424 0,3
%A A149424 Manuel Kauers (manuel(AT)kauers.de), Nov 18 2008