A180625 - cp's OEIS frontend

A180625 a(1) = 2; a(n) is twice the previous term if it is prime, otherwise the previous term minus its lowest prime factor plus one.

n	a(n)
1	2
2	4
3	3
4	6
5	5
6	10
7	9
8	7
9	14
10	13
11	26
12	25
13	21
14	19
15	38
16	37
17	74
18	73
19	146
20	145
21	141
22	139
23	278
24	277
25	554
26	553
27	547
28	1094
29	1093
30	2186
31	2185
32	2181
33	2179
34	4358
35	4357
36	8714
37	8713
38	17426
39	17425
40	17421
41	17419
42	34838
43	34837
44	34827

[2, 4, 3, 6, 5, 10, 9, 7, 14, 13, 26, 25, 21, 19, 38, 37, 74, 73, 146, 145, 141, 139, 278, 277, 554, 553, 547, 1094, 1093, 2186, 2185, 2181, 2179, 4358, 4357, 8714, 8713, 17426, 17425, 17421, 17419, 34838, 34837, 34827]

cp's OEIS Frontend

A180625 a(1) = 2; a(n) is twice the previous term if it is prime, otherwise the previous term minus its lowest prime factor plus one.

Table of values

List of values