A047176 Number of nonempty subsets of {1,2,...,n} in which exactly 1/5 of the elements are <= (n-1)/2.

0, 0, 0, 0, 0, 2, 3, 15, 20, 60, 75, 175, 210, 435, 511, 1071, 1260, 2940, 3510, 8910, 10725, 27345, 32835, 80795, 96382, 230230, 273273, 649805, 770315, 1860131, 2208115, 5426995, 6451500, 15974220

Offset

1,6

Links

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

Crossrefs

Sequence in context: A294131 A274003 A101507 * A347668 A325236 A037175

Adjacent sequences: A047173 A047174 A047175 * A047177 A047178 A047179

Keyword

nonn

Author

Clark Kimberling

Status

approved