A252461 - cp's OEIS frontend

A252461 Shift one instance of the smallest prime one step towards smaller primes: a(1) = 1, a(2n) = n, and for odd numbers > 1: a(n) = (n / prime(s)) * prime(s-1), where s = A055396(n), index of the smallest prime dividing n.

n	a(n)
1	1
2	1
3	2
4	2
5	3
6	3
7	5
8	4
9	6
10	5
11	7
12	6
13	11
14	7
15	10
16	8
17	13
18	9
19	17
20	10
21	14
22	11
23	19
24	12
25	15
26	13
27	18
28	14
29	23
30	15
31	29
32	16
33	22
34	17
35	21
36	18
37	31
38	19
39	26
40	20
41	37
42	21
43	41
44	22
45	30
46	23
47	43
48	24
49	35
50	25
51	34
52	26
53	47
54	27
55	33
56	28
57	38
58	29
59	53
60	30
61	59
62	31
63	42
64	32
65	39
66	33
67	61
68	34
69	46
70	35
71	67
72	36
73	71
74	37
75	50
76	38
77	55
78	39
79	73
80	40
81	54
82	41
83	79
84	42

[1, 1, 2, 2, 3, 3, 5, 4, 6, 5, 7, 6, 11, 7, 10, 8, 13, 9, 17, 10, 14, 11, 19, 12, 15, 13, 18, 14, 23, 15, 29, 16, 22, 17, 21, 18, 31, 19, 26, 20, 37, 21, 41, 22, 30, 23, 43, 24, 35, 25, 34, 26, 47, 27, 33, 28, 38, 29, 53, 30, 59, 31, 42, 32, 39, 33, 61, 34, 46, 35, 67, 36, 71, 37, 50, 38, 55, 39, 73, 40, 54, 41, 79, 42]

cp's OEIS Frontend

A252461 Shift one instance of the smallest prime one step towards smaller primes: a(1) = 1, a(2n) = n, and for odd numbers > 1: a(n) = (n / prime(s)) * prime(s-1), where s = A055396(n), index of the smallest prime dividing n.

Table of values

List of values

n	a(n)
1	1
2	1
3	2
4	2
5	3
6	3
7	5
8	4
9	6
10	5
11	7
12	6
13	11
14	7
15	10
16	8
17	13
18	9
19	17
20	10
21	14
22	11
23	19
24	12
25	15
26	13
27	18
28	14
29	23
30	15
31	29
32	16
33	22
34	17
35	21
36	18
37	31
38	19
39	26
40	20
41	37
42	21
43	41
44	22
45	30
46	23
47	43
48	24
49	35
50	25
51	34
52	26
53	47
54	27
55	33
56	28
57	38
58	29
59	53
60	30
61	59
62	31
63	42
64	32
65	39
66	33
67	61
68	34
69	46
70	35
71	67
72	36
73	71
74	37
75	50
76	38
77	55
78	39
79	73
80	40
81	54
82	41
83	79
84	42

n	a(n)
1	1
2	1
3	2
4	2
5	3
6	3
7	5
8	4
9	6
10	5
11	7
12	6
13	11
14	7
15	10
16	8
17	13
18	9
19	17
20	10
21	14
22	11
23	19
24	12
25	15
26	13
27	18
28	14
29	23
30	15
31	29
32	16
33	22
34	17
35	21
36	18
37	31
38	19
39	26
40	20
41	37
42	21
43	41
44	22
45	30
46	23
47	43
48	24
49	35
50	25
51	34
52	26
53	47
54	27
55	33
56	28
57	38
58	29
59	53
60	30
61	59
62	31
63	42
64	32
65	39
66	33
67	61
68	34
69	46
70	35
71	67
72	36
73	71
74	37
75	50
76	38
77	55
78	39
79	73
80	40
81	54
82	41
83	79
84	42

n	a(n)
1	1
2	1
3	2
4	2
5	3
6	3
7	5
8	4
9	6
10	5
11	7
12	6
13	11
14	7
15	10
16	8
17	13
18	9
19	17
20	10
21	14
22	11
23	19
24	12
25	15
26	13
27	18
28	14
29	23
30	15
31	29
32	16
33	22
34	17
35	21
36	18
37	31
38	19
39	26
40	20
41	37
42	21
43	41
44	22
45	30
46	23
47	43
48	24
49	35
50	25
51	34
52	26
53	47
54	27
55	33
56	28
57	38
58	29
59	53
60	30
61	59
62	31
63	42
64	32
65	39
66	33
67	61
68	34
69	46
70	35
71	67
72	36
73	71
74	37
75	50
76	38
77	55
78	39
79	73
80	40
81	54
82	41
83	79
84	42