A048516 Array T read by diagonals: T(m,n)=number of subsets S of {1,2,3,...,m+n-1} such that |S|>1 and |a-b|>=m for all distinct a and b in S, m=1,2,3,...; n=1,2,3,...

0, 0, 1, 0, 4, 1, 0, 11, 3, 1, 0, 26, 7, 3, 1, 0, 57, 14, 6, 3, 1, 0, 120, 26, 11, 6, 3, 1, 0, 247, 46, 19, 10, 6, 3, 1, 0, 502, 79, 31, 16, 10, 6, 3, 1, 0, 1013, 133, 49, 25, 15, 10, 6, 3, 1, 0, 2036, 221, 76, 38, 22, 15, 10, 6, 3, 1, 0, 4083, 364

Offset

1,5

Links

Table of n, a(n) for n=1..69.

Sean A. Irvine, Java program (github)

Formula

T(m,n) = [x^m] 1/((1-x^2)*(1-x-x^n)). - Sean A. Irvine, Jun 19 2021

Example

Diagonals: {0}; {1,0}; {4,1,0}; ...

Crossrefs

A000295 (row 1), A001924 (row 2), A050228 (row 3).

Sequence in context: A127155 A211793 A145880 * A060638 A244125 A007789

Adjacent sequences: A048513 A048514 A048515 * A048517 A048518 A048519

Keyword

nonn,tabl

Author

Clark Kimberling

Status

approved