A100394 - cp's OEIS frontend

A100394 a(n) is the subscript of the greatest prime factor of (2*prime(n) + 1).

n	a(n)
1	3
2	4
3	5
4	3
5	9
6	2
7	4
8	6
9	15
10	17
11	4
12	3
13	23
14	10
15	8
16	28
17	7
18	13
19	3
20	6
21	4
22	16
23	39
24	41
25	6
26	10
27	9
28	14
29	21
30	49
31	7
32	56
33	5
34	11
35	9
36	26
37	4
38	29
39	19
40	69
41	72
42	5
43	76
44	14
45	22
46	8
47	15
48	35
49	6
50	7
51	91
52	92
53	9
54	96
55	27
56	11
57	5
58	42
59	12
60	103
61	4
62	107
63	13
64	24
65	8
66	31
67	7
68	3
69	34
70	51
71	26
72	128
73	4
74	23
75	9
76	17
77	13
78	16
79	21
80	6

[3, 4, 5, 3, 9, 2, 4, 6, 15, 17, 4, 3, 23, 10, 8, 28, 7, 13, 3, 6, 4, 16, 39, 41, 6, 10, 9, 14, 21, 49, 7, 56, 5, 11, 9, 26, 4, 29, 19, 69, 72, 5, 76, 14, 22, 8, 15, 35, 6, 7, 91, 92, 9, 96, 27, 11, 5, 42, 12, 103, 4, 107, 13, 24, 8, 31, 7, 3, 34, 51, 26, 128, 4, 23, 9, 17, 13, 16, 21, 6]

cp's OEIS Frontend

A100394 a(n) is the subscript of the greatest prime factor of (2*prime(n) + 1).

Table of values

List of values

n	a(n)
1	3
2	4
3	5
4	3
5	9
6	2
7	4
8	6
9	15
10	17
11	4
12	3
13	23
14	10
15	8
16	28
17	7
18	13
19	3
20	6
21	4
22	16
23	39
24	41
25	6
26	10
27	9
28	14
29	21
30	49
31	7
32	56
33	5
34	11
35	9
36	26
37	4
38	29
39	19
40	69
41	72
42	5
43	76
44	14
45	22
46	8
47	15
48	35
49	6
50	7
51	91
52	92
53	9
54	96
55	27
56	11
57	5
58	42
59	12
60	103
61	4
62	107
63	13
64	24
65	8
66	31
67	7
68	3
69	34
70	51
71	26
72	128
73	4
74	23
75	9
76	17
77	13
78	16
79	21
80	6

n	a(n)
1	3
2	4
3	5
4	3
5	9
6	2
7	4
8	6
9	15
10	17
11	4
12	3
13	23
14	10
15	8
16	28
17	7
18	13
19	3
20	6
21	4
22	16
23	39
24	41
25	6
26	10
27	9
28	14
29	21
30	49
31	7
32	56
33	5
34	11
35	9
36	26
37	4
38	29
39	19
40	69
41	72
42	5
43	76
44	14
45	22
46	8
47	15
48	35
49	6
50	7
51	91
52	92
53	9
54	96
55	27
56	11
57	5
58	42
59	12
60	103
61	4
62	107
63	13
64	24
65	8
66	31
67	7
68	3
69	34
70	51
71	26
72	128
73	4
74	23
75	9
76	17
77	13
78	16
79	21
80	6

n	a(n)
1	3
2	4
3	5
4	3
5	9
6	2
7	4
8	6
9	15
10	17
11	4
12	3
13	23
14	10
15	8
16	28
17	7
18	13
19	3
20	6
21	4
22	16
23	39
24	41
25	6
26	10
27	9
28	14
29	21
30	49
31	7
32	56
33	5
34	11
35	9
36	26
37	4
38	29
39	19
40	69
41	72
42	5
43	76
44	14
45	22
46	8
47	15
48	35
49	6
50	7
51	91
52	92
53	9
54	96
55	27
56	11
57	5
58	42
59	12
60	103
61	4
62	107
63	13
64	24
65	8
66	31
67	7
68	3
69	34
70	51
71	26
72	128
73	4
74	23
75	9
76	17
77	13
78	16
79	21
80	6