A237291 - cp's OEIS frontend

A237291 Number of ways to write 2*n - 1 = p + q + r (p <= q <= r) with p, q, r, pi(p), pi(q), pi(r) all prime, where pi(x) denotes the number of primes not exceeding x (A000720).

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

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

cp's OEIS Frontend

A237291 Number of ways to write 2*n - 1 = p + q + r (p <= q <= r) with p, q, r, pi(p), pi(q), pi(r) all prime, where pi(x) denotes the number of primes not exceeding x (A000720).

Table of values

List of values

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

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

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