A177983 - cp's OEIS frontend

A177983 a(1)=3. Otherwise the average of the least prime divisors of 2n-1 and 2n+3.

n	a(n)
1	3
2	5
3	4
4	9
5	8
6	7
7	15
8	11
9	10
10	21
11	4
12	13
13	17
14	17
15	16
16	18
17	20
18	4
19	39
20	23
21	22
22	45
23	5
24	25
25	30
26	4
27	28
28	32
29	32
30	31
31	33
32	35
33	4
34	69
35	38
36	37
37	40
38	41
39	5
40	81
41	4
42	43
43	47
44	5
45	46
46	6
47	50
48	4
49	99
50	53
51	52
52	105
53	56
54	55
55	111
56	4
57	58
58	6
59	7
60	5
61	8
62	65
63	4
64	129
65	5
66	67
67	72
68	71
69	70
70	75
71	4
72	7
73	77
74	77
75	76
76	78
77	80
78	4
79	82
80	83

[3, 5, 4, 9, 8, 7, 15, 11, 10, 21, 4, 13, 17, 17, 16, 18, 20, 4, 39, 23, 22, 45, 5, 25, 30, 4, 28, 32, 32, 31, 33, 35, 4, 69, 38, 37, 40, 41, 5, 81, 4, 43, 47, 5, 46, 6, 50, 4, 99, 53, 52, 105, 56, 55, 111, 4, 58, 6, 7, 5, 8, 65, 4, 129, 5, 67, 72, 71, 70, 75, 4, 7, 77, 77, 76, 78, 80, 4, 82, 83]

cp's OEIS Frontend

A177983 a(1)=3. Otherwise the average of the least prime divisors of 2n-1 and 2n+3.

Table of values

List of values

n	a(n)
1	3
2	5
3	4
4	9
5	8
6	7
7	15
8	11
9	10
10	21
11	4
12	13
13	17
14	17
15	16
16	18
17	20
18	4
19	39
20	23
21	22
22	45
23	5
24	25
25	30
26	4
27	28
28	32
29	32
30	31
31	33
32	35
33	4
34	69
35	38
36	37
37	40
38	41
39	5
40	81
41	4
42	43
43	47
44	5
45	46
46	6
47	50
48	4
49	99
50	53
51	52
52	105
53	56
54	55
55	111
56	4
57	58
58	6
59	7
60	5
61	8
62	65
63	4
64	129
65	5
66	67
67	72
68	71
69	70
70	75
71	4
72	7
73	77
74	77
75	76
76	78
77	80
78	4
79	82
80	83

n	a(n)
1	3
2	5
3	4
4	9
5	8
6	7
7	15
8	11
9	10
10	21
11	4
12	13
13	17
14	17
15	16
16	18
17	20
18	4
19	39
20	23
21	22
22	45
23	5
24	25
25	30
26	4
27	28
28	32
29	32
30	31
31	33
32	35
33	4
34	69
35	38
36	37
37	40
38	41
39	5
40	81
41	4
42	43
43	47
44	5
45	46
46	6
47	50
48	4
49	99
50	53
51	52
52	105
53	56
54	55
55	111
56	4
57	58
58	6
59	7
60	5
61	8
62	65
63	4
64	129
65	5
66	67
67	72
68	71
69	70
70	75
71	4
72	7
73	77
74	77
75	76
76	78
77	80
78	4
79	82
80	83

n	a(n)
1	3
2	5
3	4
4	9
5	8
6	7
7	15
8	11
9	10
10	21
11	4
12	13
13	17
14	17
15	16
16	18
17	20
18	4
19	39
20	23
21	22
22	45
23	5
24	25
25	30
26	4
27	28
28	32
29	32
30	31
31	33
32	35
33	4
34	69
35	38
36	37
37	40
38	41
39	5
40	81
41	4
42	43
43	47
44	5
45	46
46	6
47	50
48	4
49	99
50	53
51	52
52	105
53	56
54	55
55	111
56	4
57	58
58	6
59	7
60	5
61	8
62	65
63	4
64	129
65	5
66	67
67	72
68	71
69	70
70	75
71	4
72	7
73	77
74	77
75	76
76	78
77	80
78	4
79	82
80	83