A210452 - cp's OEIS frontend

A210452 Number of integers k with k-1 and k+1 both prime, and k and k*n both practical.

n	a(n)
1	0
2	0
3	0
4	0
5	1
6	1
7	2
8	2
9	2
10	2
11	1
12	2
13	2
14	3
15	3
16	3
17	1
18	3
19	2
20	4
21	4
22	4
23	2
24	4
25	4
26	4
27	4
28	4
29	2
30	4
31	2
32	5
33	5
34	4
35	5
36	5
37	2
38	4
39	5
40	5
41	1
42	5
43	2
44	6
45	6
46	5
47	2
48	6
49	6
50	6
51	6
52	6
53	2
54	6
55	6
56	6
57	6
58	5
59	2
60	6
61	3
62	5
63	7
64	7
65	7
66	7
67	3
68	7
69	7
70	7
71	3
72	7
73	4
74	6
75	8
76	8
77	8
78	8
79	3
80	8
81	8
82	6
83	3
84	8
85	8
86	6
87	8
88	8
89	3
90	8
91	8
92	8
93	7
94	6
95	8
96	8
97	3
98	8
99	8
100	8

[0, 0, 0, 0, 1, 1, 2, 2, 2, 2, 1, 2, 2, 3, 3, 3, 1, 3, 2, 4, 4, 4, 2, 4, 4, 4, 4, 4, 2, 4, 2, 5, 5, 4, 5, 5, 2, 4, 5, 5, 1, 5, 2, 6, 6, 5, 2, 6, 6, 6, 6, 6, 2, 6, 6, 6, 6, 5, 2, 6, 3, 5, 7, 7, 7, 7, 3, 7, 7, 7, 3, 7, 4, 6, 8, 8, 8, 8, 3, 8, 8, 6, 3, 8, 8, 6, 8, 8, 3, 8, 8, 8, 7, 6, 8, 8, 3, 8, 8, 8]

cp's OEIS Frontend

A210452 Number of integers k with k-1 and k+1 both prime, and k and k*n both practical.

Table of values

List of values

n	a(n)
1	0
2	0
3	0
4	0
5	1
6	1
7	2
8	2
9	2
10	2
11	1
12	2
13	2
14	3
15	3
16	3
17	1
18	3
19	2
20	4
21	4
22	4
23	2
24	4
25	4
26	4
27	4
28	4
29	2
30	4
31	2
32	5
33	5
34	4
35	5
36	5
37	2
38	4
39	5
40	5
41	1
42	5
43	2
44	6
45	6
46	5
47	2
48	6
49	6
50	6
51	6
52	6
53	2
54	6
55	6
56	6
57	6
58	5
59	2
60	6
61	3
62	5
63	7
64	7
65	7
66	7
67	3
68	7
69	7
70	7
71	3
72	7
73	4
74	6
75	8
76	8
77	8
78	8
79	3
80	8
81	8
82	6
83	3
84	8
85	8
86	6
87	8
88	8
89	3
90	8
91	8
92	8
93	7
94	6
95	8
96	8
97	3
98	8
99	8
100	8

n	a(n)
1	0
2	0
3	0
4	0
5	1
6	1
7	2
8	2
9	2
10	2
11	1
12	2
13	2
14	3
15	3
16	3
17	1
18	3
19	2
20	4
21	4
22	4
23	2
24	4
25	4
26	4
27	4
28	4
29	2
30	4
31	2
32	5
33	5
34	4
35	5
36	5
37	2
38	4
39	5
40	5
41	1
42	5
43	2
44	6
45	6
46	5
47	2
48	6
49	6
50	6
51	6
52	6
53	2
54	6
55	6
56	6
57	6
58	5
59	2
60	6
61	3
62	5
63	7
64	7
65	7
66	7
67	3
68	7
69	7
70	7
71	3
72	7
73	4
74	6
75	8
76	8
77	8
78	8
79	3
80	8
81	8
82	6
83	3
84	8
85	8
86	6
87	8
88	8
89	3
90	8
91	8
92	8
93	7
94	6
95	8
96	8
97	3
98	8
99	8
100	8

n	a(n)
1	0
2	0
3	0
4	0
5	1
6	1
7	2
8	2
9	2
10	2
11	1
12	2
13	2
14	3
15	3
16	3
17	1
18	3
19	2
20	4
21	4
22	4
23	2
24	4
25	4
26	4
27	4
28	4
29	2
30	4
31	2
32	5
33	5
34	4
35	5
36	5
37	2
38	4
39	5
40	5
41	1
42	5
43	2
44	6
45	6
46	5
47	2
48	6
49	6
50	6
51	6
52	6
53	2
54	6
55	6
56	6
57	6
58	5
59	2
60	6
61	3
62	5
63	7
64	7
65	7
66	7
67	3
68	7
69	7
70	7
71	3
72	7
73	4
74	6
75	8
76	8
77	8
78	8
79	3
80	8
81	8
82	6
83	3
84	8
85	8
86	6
87	8
88	8
89	3
90	8
91	8
92	8
93	7
94	6
95	8
96	8
97	3
98	8
99	8
100	8