1430715

Appears in sequences

• a(n) = binomial(3*n,n)/(2*n+1) (enumerates ternary trees and also noncrossing trees).at n=10A001764
• a(n) = floor( binomial(n,9)/10 ).at n=30A011846
• Number of aperiodic necklaces of n beads of 2 colors, 10 of them black.at n=20A032168
• Number of necklaces with 10 black beads and n-10 white beads.at n=21A032195
• 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=20A047749
• Number of dissectable polyhedra with n tetrahedral cells and symmetry of type F.at n=38A047760
• a(n) = A047760(2n+1).at n=19A047761
• Number of dissectable polyhedra with n tetrahedral cells and symmetry of type P.at n=39A047765
• a(n) = A047765(2n).at n=19A047767
• Interpolation of A001764(n+1) and A006629(n).at n=18A124817
• Triangle of Generalized Runyon numbers R_{n,k}^(3) read by rows.at n=54A173020
• 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=54A232223
• a(n) = binomial(6*n, 2*n) / (4*n + 1).at n=5A235534
• Triangle read by rows: the reversed x = 1+q Narayana triangle at m=2.at n=45A243662
• Number of Dyck paths of semilength n having exactly ten (possibly overlapping) occurrences of the consecutive step pattern given by the binary expansion of n, where 1=U=(1,1) and 0=D=(1,-1).at n=25A243779
• Number of order ideals of type e^(1)_n.at n=17A299295
• Number of words of length 3n such that all letters of the denary alphabet occur at least once and are introduced in ascending order and which can be built by repeatedly inserting triples of identical letters into the initially empty word.at n=0A321040
• Numbers k such that both k and k+1 are recursive abundant numbers (A333928).at n=27A333951
• a(n) = binomial(A007310(n+1),n)/A007310(n+1).at n=10A367520
• a(n) is the least k such that there are exactly n solutions in positive integers to the equation x^3 + y^2 = k^2.at n=13A382838