A047177 - OEIS

The OEIS is supported by the many generous donors to the OEIS Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Other ways to Give

A047177

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

0, 0, 0, 0, 1, 4, 12, 30, 60, 121, 205, 385, 630, 1260, 2156, 4711, 8260, 18340, 31620, 68772, 115995, 250185, 418825, 914485, 1535391, 3405402, 5728086, 12788516, 21448791, 47902764, 80006668, 178864378, 298009048, 668688388

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,6

LINKS

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

CROSSREFS

Sequence in context: A008261 A099407 A011938 * A048077 A350424 A220264

Adjacent sequences: A047174 A047175 A047176 * A047178 A047179 A047180

KEYWORD

nonn

AUTHOR

Clark Kimberling

STATUS

approved