A027421 Triangle T(n,k) = number of distinct products ij with k<=i,j<=n, for 0<=k<=n.

1, 2, 1, 4, 3, 1, 7, 6, 3, 1, 10, 9, 6, 3, 1, 15, 14, 10, 6, 3, 1, 19, 18, 14, 10, 6, 3, 1, 26, 25, 20, 15, 10, 6, 3, 1, 31, 30, 25, 20, 15, 10, 6, 3, 1, 37, 36, 31, 26, 20, 15, 10, 6, 3, 1, 43, 42, 37, 32, 26, 21, 15, 10, 6, 3, 1, 54, 53, 47, 41, 34, 28, 21, 15, 10, 6, 3, 1

Offset

0,2

Links

Table of n, a(n) for n=0..77.

Example

1; 2,1; 4,3,1; 7,6,3,1; 10,9,6,3,1; ...

Crossrefs

Cf. A027384, A027422.

Sequence in context: A107661 A126570 A048790 * A131252 A345123 A133805

Adjacent sequences: A027418 A027419 A027420 * A027422 A027423 A027424

Keyword

tabl,nonn,easy

Author

N. J. A. Sloane.

Extensions

More terms from Olivier Gérard, Nov 15 1997

Status

approved