138866

Appears in sequences

• Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= n/3.at n=20A047196
• Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n+1)/3.at n=20A048041
• Number of nonempty subsets of {1,2,...,n} in which exactly 1/4 of the elements are <= (n+2)/3.at n=20A048074
• Expansion of Product_{k>=1} ((1 + x^k)/(1 - x^k))^(k*(k+1)/2).at n=12A302237
• Triangle read by rows: T(n,k) is the number of open meanders with 2n crossings and k exterior top arches, 0 <= k <= n.at n=61A380369