A191280 - cp's OEIS frontend

A191280 a(0)=1; for n>0, p2(n)+Sum(binomial(2k,k)p2(n-k)/2,k=1..n-1) where p2 = A002995, the number of unlabeled planar trees on n nodes.

n	a(n)
0	1
1	1
2	2
3	6
4	18
5	60
6	210
7	754
8	2766
9	10280
10	38568
11	145770
12	554162
13	2116568
14	8115660
15	31220672
16	120442860
17	465775226
18	1805074882
19	7008550224
20	27257398714
21	106166467074
22	414068416752
23	1616899329454
24	6320798698322
25	24734167234028
26	96877398455260
27	379765373701964
28	1489867265555382
29	5849164981941642
30	22979031257945948

[1, 1, 2, 6, 18, 60, 210, 754, 2766, 10280, 38568, 145770, 554162, 2116568, 8115660, 31220672, 120442860, 465775226, 1805074882, 7008550224, 27257398714, 106166467074, 414068416752, 1616899329454, 6320798698322, 24734167234028, 96877398455260, 379765373701964, 1489867265555382, 5849164981941642, 22979031257945948]

cp's OEIS Frontend

A191280 a(0)=1; for n>0, p2(n)+Sum(binomial(2k,k)p2(n-k)/2,k=1..n-1) where p2 = A002995, the number of unlabeled planar trees on n nodes.

Table of values

List of values

cp's OEIS Frontend

A191280 a(0)=1; for n>0, p2(n)+Sum(binomial(2*k,k)*p2(n-k)/2,k=1..n-1) where p2 = A002995, the number of unlabeled planar trees on n nodes.

Table of values

List of values

A191280 a(0)=1; for n>0, p2(n)+Sum(binomial(2k,k)p2(n-k)/2,k=1..n-1) where p2 = A002995, the number of unlabeled planar trees on n nodes.