A080356 - cp's OEIS frontend

A080356 Number of twin primes between n and 2n: a(n) = number of j in range n <= j <= 2*n such that j and j+2 are primes.

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	1
8	1
9	2
10	2
11	2
12	1
13	1
14	1
15	2
16	2
17	2
18	1
19	1
20	1
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2
31	2
32	2
33	2
34	2
35	2
36	3
37	3
38	3
39	3
40	3
41	3
42	2
43	2
44	2
45	2
46	2
47	2
48	2
49	2
50	2
51	3
52	3
53	3
54	4
55	4
56	4
57	4
58	4
59	4
60	3
61	3
62	3
63	3
64	3
65	3
66	3
67	3
68	3
69	4
70	4
71	4
72	3
73	3
74	3
75	4
76	4
77	4
78	4
79	4
80	4
81	4
82	4
83	4
84	4
85	4
86	4
87	4
88	4
89	4
90	5
91	5
92	5
93	5
94	5
95	5
96	6
97	6
98	6
99	7
100	7
101	7
102	6
103	6
104	6
105	6

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

cp's OEIS Frontend

A080356 Number of twin primes between n and 2n: a(n) = number of j in range n <= j <= 2*n such that j and j+2 are primes.

Table of values

List of values

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	1
8	1
9	2
10	2
11	2
12	1
13	1
14	1
15	2
16	2
17	2
18	1
19	1
20	1
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2
31	2
32	2
33	2
34	2
35	2
36	3
37	3
38	3
39	3
40	3
41	3
42	2
43	2
44	2
45	2
46	2
47	2
48	2
49	2
50	2
51	3
52	3
53	3
54	4
55	4
56	4
57	4
58	4
59	4
60	3
61	3
62	3
63	3
64	3
65	3
66	3
67	3
68	3
69	4
70	4
71	4
72	3
73	3
74	3
75	4
76	4
77	4
78	4
79	4
80	4
81	4
82	4
83	4
84	4
85	4
86	4
87	4
88	4
89	4
90	5
91	5
92	5
93	5
94	5
95	5
96	6
97	6
98	6
99	7
100	7
101	7
102	6
103	6
104	6
105	6

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	1
8	1
9	2
10	2
11	2
12	1
13	1
14	1
15	2
16	2
17	2
18	1
19	1
20	1
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2
31	2
32	2
33	2
34	2
35	2
36	3
37	3
38	3
39	3
40	3
41	3
42	2
43	2
44	2
45	2
46	2
47	2
48	2
49	2
50	2
51	3
52	3
53	3
54	4
55	4
56	4
57	4
58	4
59	4
60	3
61	3
62	3
63	3
64	3
65	3
66	3
67	3
68	3
69	4
70	4
71	4
72	3
73	3
74	3
75	4
76	4
77	4
78	4
79	4
80	4
81	4
82	4
83	4
84	4
85	4
86	4
87	4
88	4
89	4
90	5
91	5
92	5
93	5
94	5
95	5
96	6
97	6
98	6
99	7
100	7
101	7
102	6
103	6
104	6
105	6

n	a(n)
1	0
2	1
3	2
4	1
5	1
6	1
7	1
8	1
9	2
10	2
11	2
12	1
13	1
14	1
15	2
16	2
17	2
18	1
19	1
20	1
21	2
22	2
23	2
24	2
25	2
26	2
27	2
28	2
29	2
30	2
31	2
32	2
33	2
34	2
35	2
36	3
37	3
38	3
39	3
40	3
41	3
42	2
43	2
44	2
45	2
46	2
47	2
48	2
49	2
50	2
51	3
52	3
53	3
54	4
55	4
56	4
57	4
58	4
59	4
60	3
61	3
62	3
63	3
64	3
65	3
66	3
67	3
68	3
69	4
70	4
71	4
72	3
73	3
74	3
75	4
76	4
77	4
78	4
79	4
80	4
81	4
82	4
83	4
84	4
85	4
86	4
87	4
88	4
89	4
90	5
91	5
92	5
93	5
94	5
95	5
96	6
97	6
98	6
99	7
100	7
101	7
102	6
103	6
104	6
105	6