A059975 - cp's OEIS frontend

A059975 For n > 1, a(n) is the least number of prime factors (counted with multiplicity) of any integer with n divisors; fully additive with a(p) = p-1.

n	a(n)
1	0
2	1
3	2
4	2
5	4
6	3
7	6
8	3
9	4
10	5
11	10
12	4
13	12
14	7
15	6
16	4
17	16
18	5
19	18
20	6
21	8
22	11
23	22
24	5
25	8
26	13
27	6
28	8
29	28
30	7
31	30
32	5
33	12
34	17
35	10
36	6
37	36
38	19
39	14
40	7
41	40
42	9
43	42
44	12
45	8
46	23
47	46
48	6
49	12
50	9
51	18
52	14
53	52
54	7
55	14
56	9
57	20
58	29
59	58
60	8
61	60
62	31
63	10
64	6
65	16
66	13
67	66
68	18
69	24
70	11
71	70
72	7
73	72
74	37
75	10
76	20
77	16
78	15
79	78
80	8
81	8
82	41

[0, 1, 2, 2, 4, 3, 6, 3, 4, 5, 10, 4, 12, 7, 6, 4, 16, 5, 18, 6, 8, 11, 22, 5, 8, 13, 6, 8, 28, 7, 30, 5, 12, 17, 10, 6, 36, 19, 14, 7, 40, 9, 42, 12, 8, 23, 46, 6, 12, 9, 18, 14, 52, 7, 14, 9, 20, 29, 58, 8, 60, 31, 10, 6, 16, 13, 66, 18, 24, 11, 70, 7, 72, 37, 10, 20, 16, 15, 78, 8, 8, 41]

cp's OEIS Frontend

A059975 For n > 1, a(n) is the least number of prime factors (counted with multiplicity) of any integer with n divisors; fully additive with a(p) = p-1.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	2
5	4
6	3
7	6
8	3
9	4
10	5
11	10
12	4
13	12
14	7
15	6
16	4
17	16
18	5
19	18
20	6
21	8
22	11
23	22
24	5
25	8
26	13
27	6
28	8
29	28
30	7
31	30
32	5
33	12
34	17
35	10
36	6
37	36
38	19
39	14
40	7
41	40
42	9
43	42
44	12
45	8
46	23
47	46
48	6
49	12
50	9
51	18
52	14
53	52
54	7
55	14
56	9
57	20
58	29
59	58
60	8
61	60
62	31
63	10
64	6
65	16
66	13
67	66
68	18
69	24
70	11
71	70
72	7
73	72
74	37
75	10
76	20
77	16
78	15
79	78
80	8
81	8
82	41

n	a(n)
1	0
2	1
3	2
4	2
5	4
6	3
7	6
8	3
9	4
10	5
11	10
12	4
13	12
14	7
15	6
16	4
17	16
18	5
19	18
20	6
21	8
22	11
23	22
24	5
25	8
26	13
27	6
28	8
29	28
30	7
31	30
32	5
33	12
34	17
35	10
36	6
37	36
38	19
39	14
40	7
41	40
42	9
43	42
44	12
45	8
46	23
47	46
48	6
49	12
50	9
51	18
52	14
53	52
54	7
55	14
56	9
57	20
58	29
59	58
60	8
61	60
62	31
63	10
64	6
65	16
66	13
67	66
68	18
69	24
70	11
71	70
72	7
73	72
74	37
75	10
76	20
77	16
78	15
79	78
80	8
81	8
82	41

n	a(n)
1	0
2	1
3	2
4	2
5	4
6	3
7	6
8	3
9	4
10	5
11	10
12	4
13	12
14	7
15	6
16	4
17	16
18	5
19	18
20	6
21	8
22	11
23	22
24	5
25	8
26	13
27	6
28	8
29	28
30	7
31	30
32	5
33	12
34	17
35	10
36	6
37	36
38	19
39	14
40	7
41	40
42	9
43	42
44	12
45	8
46	23
47	46
48	6
49	12
50	9
51	18
52	14
53	52
54	7
55	14
56	9
57	20
58	29
59	58
60	8
61	60
62	31
63	10
64	6
65	16
66	13
67	66
68	18
69	24
70	11
71	70
72	7
73	72
74	37
75	10
76	20
77	16
78	15
79	78
80	8
81	8
82	41