A047199 Number of nonempty subsets of {1,2,...,n} in which exactly 2/5 of the elements are <= n/3.

0, 0, 0, 0, 0, 4, 10, 20, 60, 105, 168, 364, 588, 930, 2250, 3960, 6820, 17380, 30745, 52507, 126763, 219765, 372120, 898380, 1572228, 2702252, 6619596, 11666760, 20167170, 49146654, 86461704, 149465844, 363087604, 639438019

Offset

1,6

Links

Table of n, a(n) for n=1..34.

Crossrefs

Sequence in context: A032275 A220828 A015220 * A038065 A249975 A306158

Adjacent sequences: A047196 A047197 A047198 * A047200 A047201 A047202

Keyword

nonn

Author

Clark Kimberling

Status

approved