A016121 - cp's OEIS frontend

A016121 Number of sequences (a_1, a_2, ..., a_n) of length n with a_1 = 1 satisfying a_i <= a_{i+1} <= 2*a_i.

n	a(n)
0	1
1	2
2	5
3	17
4	86
5	698
6	9551
7	226592
8	9471845
9	705154187
10	94285792211
11	22807963405043
12	10047909839840456
13	8110620438438750647
14	12062839548612627177590
15	33226539134943667506533207
16	170288915434579567358828997806
17	1630770670148598007261992936663653

[1, 2, 5, 17, 86, 698, 9551, 226592, 9471845, 705154187, 94285792211, 22807963405043, 10047909839840456, 8110620438438750647, 12062839548612627177590, 33226539134943667506533207, 170288915434579567358828997806, 1630770670148598007261992936663653]

cp's OEIS Frontend

A016121 Number of sequences (a_1, a_2, ..., a_n) of length n with a_1 = 1 satisfying a_i <= a_{i+1} <= 2*a_i.

Table of values

List of values