2399040

Appears in sequences

• a(n) = OrdinaryUnitarySigma(a(n-1)).at n=18A126850
• Number of singletons (strong fixed points) in pair-partitions.at n=8A233481
• The Riordan square of the double factorial of odd numbers. Triangle T(n, k), 0 <= k <= n, read by rows.at n=37A321627
• Triangle read by rows: T(n,k) is the number of linear chord diagrams on 2n vertices with one marked chord such that exactly k of the remaining n-1 chords cross the marked chord.at n=28A336598
• E.g.f. satisfies A(x) = exp(x^3*A(x)^2) / (1-x).at n=8A371040