%I #7 Jul 11 2015 00:16:10

%S 0,0,1,0,0,1,0,2,1,0,0,1,0,2,1,0,3,2,1,0,0,1,0,2,1,0,3,2,1,0,4,3,2,1,

%T 0,0,1,0,2,1,0,3,2,1,0,4,3,2,1,0,5,4,3,2,1,0,0,1,0,2,1,0,3,2,1,0,4,3,

%U 2,1,0,5,4,3,2,1,0,6,5,4,3,2,1,0,0,1,0,2,1,0,3,2,1,0,4,3,2,1,0,5,4,3,2,1,0

%N Tetrahedron with T(t,n,k)=n-k; succession of growing finite triangles with increasing values towards bottom left.

%F a(n) = A056557(n) - A056558(n).

%e First triangle: [0]; second triangle: [0; 1 0]; third triangle: [0; 1 0; 2 1 0]; ...

%Y Together with A056558 and A056559 might enable reading "by antidiagonals" of cube arrays as 3-dimensional analog of A002262 and A025581 with square arrays.

%K nonn

%O 0,8

%A _Henry Bottomley_, Jun 26 2000