A001764 - cp's OEIS frontend

A001764 a(n) = binomial(3n,n)/(2n+1) (enumerates ternary trees and also noncrossing trees).

n	a(n)
0	1
1	1
2	3
3	12
4	55
5	273
6	1428
7	7752
8	43263
9	246675
10	1430715
11	8414640
12	50067108
13	300830572
14	1822766520
15	11124755664
16	68328754959
17	422030545335
18	2619631042665
19	16332922290300
20	102240109897695
21	642312451217745
22	4048514844039120
23	25594403741131680
24	162250238001816900

[1, 1, 3, 12, 55, 273, 1428, 7752, 43263, 246675, 1430715, 8414640, 50067108, 300830572, 1822766520, 11124755664, 68328754959, 422030545335, 2619631042665, 16332922290300, 102240109897695, 642312451217745, 4048514844039120, 25594403741131680, 162250238001816900]

cp's OEIS Frontend

A001764 a(n) = binomial(3n,n)/(2n+1) (enumerates ternary trees and also noncrossing trees).

Table of values

List of values

cp's OEIS Frontend

A001764 a(n) = binomial(3*n,n)/(2*n+1) (enumerates ternary trees and also noncrossing trees).

Table of values

List of values

A001764 a(n) = binomial(3n,n)/(2n+1) (enumerates ternary trees and also noncrossing trees).