A331603 - cp's OEIS frontend

A331603 a(1) = 1; for n > 1, if a(n-1) is composite then a(n) is the concatenation of all the prime factors in order of a(n-1), otherwise a(n) is the smallest number not yet appearing in the sequence.

n	a(n)
1	1
2	2
3	3
4	4
5	22
6	211
7	5
8	6
9	23
10	7
11	8
12	222
13	2337
14	31941
15	33371313
16	311123771
17	7149317941
18	22931219729
19	112084656339
20	3347911118189
21	11613496501723
22	97130517917327
23	531832651281459
24	3331113965338635107
25	9
26	33
27	311
28	10
29	25
30	55
31	511
32	773
33	11
34	12
35	223
36	13
37	14
38	27
39	333
40	3337
41	4771
42	13367
43	15

[1, 2, 3, 4, 22, 211, 5, 6, 23, 7, 8, 222, 2337, 31941, 33371313, 311123771, 7149317941, 22931219729, 112084656339, 3347911118189, 11613496501723, 97130517917327, 531832651281459, 3331113965338635107, 9, 33, 311, 10, 25, 55, 511, 773, 11, 12, 223, 13, 14, 27, 333, 3337, 4771, 13367, 15]

cp's OEIS Frontend

A331603 a(1) = 1; for n > 1, if a(n-1) is composite then a(n) is the concatenation of all the prime factors in order of a(n-1), otherwise a(n) is the smallest number not yet appearing in the sequence.

Table of values

List of values