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A227673 Number of lattice paths from {n}^n to {0}^n using steps that decrement one component by 1 such that for each point (p_1,p_2,...,p_n) we have abs(p_{i}-p_{i+1}) <= 1.

%I A227673 #6 Jul 19 2013 17:22:53
%S A227673 1,1,4,320,1281696,482913033152,27297846037161958056,
%T A227673 337320253484345016223956919936,
%U A227673 1248760044848501400078426452469652899962528,1817025580455577353700768095528219275036151622984555026720
%N A227673 Number of lattice paths from {n}^n to {0}^n using steps that decrement one component by 1 such that for each point (p_1,p_2,...,p_n) we have abs(p_{i}-p_{i+1}) <= 1.
%e A227673 a(0) = 1: () .
%e A227673 a(1) = 1: (1)-(0) .
%e A227673 .               (1,2)       (0,1)
%e A227673 .              /     \     /     \
%e A227673 a(2) = 4: (2,2)       (1,1)       (0,0) .
%e A227673 .              \     /     \     /
%e A227673 .               (2,1)       (1,0)
%Y A227673 Main diagonal of A227655.
%K A227673 nonn
%O A227673 0,3
%A A227673 _Alois P. Heinz_, Jul 19 2013