A054250 Triangular array T(n,0)= 1, T(n,k) = sum_{j=1..min(n,k)} (n-j+1)*T(j,k-j) if k>0.

1, 1, 1, 1, 2, 3, 1, 3, 5, 8, 1, 4, 7, 12, 20, 1, 5, 9, 16, 28, 45, 1, 6, 11, 20, 36, 60, 95, 1, 7, 13, 24, 44, 75, 122, 191, 1, 8, 15, 28, 52, 90, 149, 238, 365, 1, 9, 17, 32, 60, 105, 176, 285, 444, 676, 1, 10, 19, 36, 68, 120, 203, 332, 523, 806, 1211

Offset: 0

Author

N. J. A. Sloane, May 06 2000

Keywords

• nonn
• tabl
• easy

Examples

			1; 1,1; 1,2,3; 1,3,5,8; 1,4,7,12,20; ...
		

Crossrefs

Used in A001523.

Programs

Maple

A054250 := proc(n,k) option remember; local j; if k = 0 then RETURN(1) else add( (n-j+1)*A054250(j,k-j), j=1..min(n,k) ); fi; end;