A235645 - cp's OEIS frontend

A235645 From Goldbach's conjecture and Chen's theorem: number of decompositions of 2n as the sum of either two primes, or a prime and a semiprime.

n	a(n)
1	0
2	1
3	1
4	1
5	2
6	1
7	2
8	2
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	3
17	5
18	4
19	3
20	3
21	4
22	5
23	5
24	5
25	5
26	5
27	5
28	4
29	6
30	6
31	5
32	6
33	6
34	4
35	6
36	7
37	8
38	8
39	8
40	7
41	9
42	8
43	8
44	7
45	9
46	8
47	9
48	8
49	6
50	9
51	9
52	10
53	10
54	9
55	9
56	12
57	12
58	11
59	13
60	12
61	10
62	11
63	11
64	9
65	12
66	11
67	12
68	11
69	11
70	12
71	15
72	14
73	12
74	12
75	12

[0, 1, 1, 1, 2, 1, 2, 2, 2, 2, 3, 3, 3, 2, 3, 3, 5, 4, 3, 3, 4, 5, 5, 5, 5, 5, 5, 4, 6, 6, 5, 6, 6, 4, 6, 7, 8, 8, 8, 7, 9, 8, 8, 7, 9, 8, 9, 8, 6, 9, 9, 10, 10, 9, 9, 12, 12, 11, 13, 12, 10, 11, 11, 9, 12, 11, 12, 11, 11, 12, 15, 14, 12, 12, 12]

cp's OEIS Frontend

A235645 From Goldbach's conjecture and Chen's theorem: number of decompositions of 2n as the sum of either two primes, or a prime and a semiprime.

Table of values

List of values

n	a(n)
1	0
2	1
3	1
4	1
5	2
6	1
7	2
8	2
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	3
17	5
18	4
19	3
20	3
21	4
22	5
23	5
24	5
25	5
26	5
27	5
28	4
29	6
30	6
31	5
32	6
33	6
34	4
35	6
36	7
37	8
38	8
39	8
40	7
41	9
42	8
43	8
44	7
45	9
46	8
47	9
48	8
49	6
50	9
51	9
52	10
53	10
54	9
55	9
56	12
57	12
58	11
59	13
60	12
61	10
62	11
63	11
64	9
65	12
66	11
67	12
68	11
69	11
70	12
71	15
72	14
73	12
74	12
75	12

n	a(n)
1	0
2	1
3	1
4	1
5	2
6	1
7	2
8	2
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	3
17	5
18	4
19	3
20	3
21	4
22	5
23	5
24	5
25	5
26	5
27	5
28	4
29	6
30	6
31	5
32	6
33	6
34	4
35	6
36	7
37	8
38	8
39	8
40	7
41	9
42	8
43	8
44	7
45	9
46	8
47	9
48	8
49	6
50	9
51	9
52	10
53	10
54	9
55	9
56	12
57	12
58	11
59	13
60	12
61	10
62	11
63	11
64	9
65	12
66	11
67	12
68	11
69	11
70	12
71	15
72	14
73	12
74	12
75	12

n	a(n)
1	0
2	1
3	1
4	1
5	2
6	1
7	2
8	2
9	2
10	2
11	3
12	3
13	3
14	2
15	3
16	3
17	5
18	4
19	3
20	3
21	4
22	5
23	5
24	5
25	5
26	5
27	5
28	4
29	6
30	6
31	5
32	6
33	6
34	4
35	6
36	7
37	8
38	8
39	8
40	7
41	9
42	8
43	8
44	7
45	9
46	8
47	9
48	8
49	6
50	9
51	9
52	10
53	10
54	9
55	9
56	12
57	12
58	11
59	13
60	12
61	10
62	11
63	11
64	9
65	12
66	11
67	12
68	11
69	11
70	12
71	15
72	14
73	12
74	12
75	12