138391

Appears in sequences

• Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n+1)/3.at n=34A048046
• Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n+2)/3.at n=34A048079
• Number of nonempty subsets of {1,2,...,n} in which exactly 4/5 of the elements are <= (n+3)/3.at n=34A048090
• a(n) = n*(n + 1)*(13*n^2 + 13*n - 14)/24.at n=22A264888