A131208 - cp's OEIS frontend

A131208 Greatest prime divisor of all composite numbers between n-th semiprime and next semiprime, or 1 if there are no such composite numbers.

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

[1, 2, 1, 3, 1, 5, 1, 3, 1, 7, 1, 1, 3, 1, 11, 3, 5, 13, 7, 1, 5, 7, 17, 7, 19, 13, 7, 1, 1, 11, 23, 1, 1, 17, 11, 19, 29, 1, 5, 1, 1, 31, 13, 1, 23, 1, 1, 3, 1, 37, 13, 1, 5, 41, 7, 43, 1, 13, 23, 31, 47, 13, 1, 1, 17, 1, 23, 53, 1, 1, 3, 1, 1, 11, 37, 29, 59, 61, 31, 7]

cp's OEIS Frontend

A131208 Greatest prime divisor of all composite numbers between n-th semiprime and next semiprime, or 1 if there are no such composite numbers.

Table of values

List of values

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

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

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