A131893 - cp's OEIS frontend

A131893 a(n) is the number of shapes of balanced trees with constant branching factor 7 and n nodes. The node is balanced if the size, measured in nodes, of each pair of its children differ by at most one node.

n	a(n)
0	1
1	1
2	7
3	21
4	35
5	35
6	21
7	7
8	1
9	49
10	1029
11	12005
12	84035
13	352947
14	823543
15	823543
16	17294403
17	155649627
18	778248135
19	2334744405
20	4202539929
21	4202539929
22	1801088541
23	21012699645
24	105063498225
25	291843050625
26	486405084375
27	486405084375
28	270225046875
29	64339296875

[1, 1, 7, 21, 35, 35, 21, 7, 1, 49, 1029, 12005, 84035, 352947, 823543, 823543, 17294403, 155649627, 778248135, 2334744405, 4202539929, 4202539929, 1801088541, 21012699645, 105063498225, 291843050625, 486405084375, 486405084375, 270225046875, 64339296875]

cp's OEIS Frontend

A131893 a(n) is the number of shapes of balanced trees with constant branching factor 7 and n nodes. The node is balanced if the size, measured in nodes, of each pair of its children differ by at most one node.

Table of values

List of values