8414640

Appears in sequences

• a(n) = binomial(3*n,n)/(2*n+1) (enumerates ternary trees and also noncrossing trees).at n=11A001764
• Number of aperiodic necklaces of n beads of 2 colors, 11 of them black.at n=22A032169
• Number of necklaces with 11 black beads and n-11 white beads.at n=23A032196
• If n = 2*m then a(n) = binomial(3*m, m)/(2*m+1), if n=2*m+1 then a(n) = binomial(3*m+1, m+1)/(2*m+1).at n=22A047749
• Number of dissectable polyhedra with n tetrahedral cells and symmetry of type F.at n=42A047760
• a(n) = A047760(2n+1).at n=21A047761
• Interpolation of A001764(n+1) and A006629(n).at n=20A124817
• Expansion of series reversion of generating function for triangular numbers.at n=11A179848
• Triangle read by rows: T(n,k) = number of connected matchings with n crossings and k chords, in a disk, k=2..n+1.at n=65A232223
• Number of order ideals of type e^(1)_n.at n=19A299295
• Numbers k with at least two divisors d for which sigma(k) = d*sigma(d).at n=8A344102