A063895 - cp's OEIS frontend

A063895 Start with x, xy; then concatenate each word in turn with all preceding words, getting x xy xxy xxxy xyxxy xxxxy xyxxxy xxyxxxy ...; sequence gives number of words of length n. Also binary trees by degree: x (x,y) (x,(x,y)) (x,(x,(x,y))) ((x,y),(x,(x,y)))...

n	a(n)
1	1
2	1
3	1
4	1
5	2
6	3
7	6
8	11
9	22
10	43
11	88
12	179
13	372
14	774
15	1631
16	3448
17	7347
18	15713
19	33791
20	72923
21	158021
22	343495
23	749102
24	1638103
25	3591724
26	7893802
27	17387931
28	38379200
29	84875596
30	188036830
31	417284181
32	927469845
33	2064465341
34	4601670625
35	10270463565
36	22950838755

[1, 1, 1, 1, 2, 3, 6, 11, 22, 43, 88, 179, 372, 774, 1631, 3448, 7347, 15713, 33791, 72923, 158021, 343495, 749102, 1638103, 3591724, 7893802, 17387931, 38379200, 84875596, 188036830, 417284181, 927469845, 2064465341, 4601670625, 10270463565, 22950838755]

cp's OEIS Frontend

A063895 Start with x, xy; then concatenate each word in turn with all preceding words, getting x xy xxy xxxy xyxxy xxxxy xyxxxy xxyxxxy ...; sequence gives number of words of length n. Also binary trees by degree: x (x,y) (x,(x,y)) (x,(x,(x,y))) ((x,y),(x,(x,y)))...

Table of values

List of values