A334816 - cp's OEIS frontend

A334816 Least number that reaches 1 after n iterations of the map k -> usigma(k)/ud(k) if ud(k) | usigma(k), and k -> 1 otherwise, where ud(k) is the number of unitary divisors of k (A034444) and usigma(k) is their sum (A034448).

n	a(n)
0	1
1	2
2	3
3	5
4	9
5	17
6	43
7	137
8	281
9	673
10	2401
11	4801
12	9601
13	170761
14	341521
15	683041
16	5114881
17	31846081
18	131955841
19	1985902081
20	7545868801

[1, 2, 3, 5, 9, 17, 43, 137, 281, 673, 2401, 4801, 9601, 170761, 341521, 683041, 5114881, 31846081, 131955841, 1985902081, 7545868801]