login
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, 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
OFFSET
1,6
CROSSREFS
Sequence in context: A008261 A099407 A011938 * A048077 A350424 A220264
KEYWORD
nonn
STATUS
approved