A063380 - cp's OEIS frontend

A063380 a(1) = 4, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

n	a(n)
1	4
2	22
3	211
4	1211
5	7173
6	9797
7	97101
8	910789
9	1182799
10	1319029
11	6719687
12	7678761
13	32559587
14	257126691
15	1591617149
16	6653239233
17	62767105999
18	126149775659
19	432933715713
20	2435717774509
21	6598336914323
22	19495633384521

[4, 22, 211, 1211, 7173, 9797, 97101, 910789, 1182799, 1319029, 6719687, 7678761, 32559587, 257126691, 1591617149, 6653239233, 62767105999, 126149775659, 432933715713, 2435717774509, 6598336914323, 19495633384521]

cp's OEIS Frontend

A063380 a(1) = 4, a(n) = concatenation of two closest factors of a(n-1) whose product equals a(n-1) or if a(n-1) is a prime then the concatenation of 1 and a(n-1).

Table of values

List of values