A087712 - cp's OEIS frontend

A087712 a(1) = 1; if n = k-th prime, a(n) = k; otherwise write all prime factors of n in nondecreasing order, replace each prime with its rank, and concatenate the ranks.

n	a(n)
1	1
2	1
3	2
4	11
5	3
6	12
7	4
8	111
9	22
10	13
11	5
12	112
13	6
14	14
15	23
16	1111
17	7
18	122
19	8
20	113
21	24
22	15
23	9
24	1112
25	33
26	16
27	222
28	114
29	10
30	123
31	11
32	11111
33	25
34	17
35	34
36	1122
37	12
38	18
39	26
40	1113
41	13
42	124
43	14
44	115
45	223
46	19
47	15
48	11112
49	44
50	133
51	27
52	116
53	16
54	1222
55	35
56	1114
57	28
58	110
59	17
60	1123
61	18

[1, 1, 2, 11, 3, 12, 4, 111, 22, 13, 5, 112, 6, 14, 23, 1111, 7, 122, 8, 113, 24, 15, 9, 1112, 33, 16, 222, 114, 10, 123, 11, 11111, 25, 17, 34, 1122, 12, 18, 26, 1113, 13, 124, 14, 115, 223, 19, 15, 11112, 44, 133, 27, 116, 16, 1222, 35, 1114, 28, 110, 17, 1123, 18]

cp's OEIS Frontend

A087712 a(1) = 1; if n = k-th prime, a(n) = k; otherwise write all prime factors of n in nondecreasing order, replace each prime with its rank, and concatenate the ranks.

Table of values

List of values