A262403 - cp's OEIS frontend

A262403 Number of ways to write pi(T(n)) = pi(T(k)) + pi(T(m)) with 1 < k < m < n, where T(x) is the triangular number x*(x+1)/2, and pi(x) is the number of primes not exceeding x.

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

[0, 0, 0, 0, 1, 1, 1, 2, 2, 1, 2, 1, 3, 4, 4, 4, 3, 3, 3, 3, 5, 4, 3, 4, 6, 4, 5, 2, 3, 6, 4, 1, 5, 8, 3, 2, 6, 1, 4, 5, 4, 2, 7, 2, 4, 5, 5, 5, 3, 4, 9, 9, 4, 5, 4, 8, 7, 6, 9, 4, 7, 5, 6, 2, 5, 9, 3, 8, 5, 6, 8, 5, 4, 3, 8, 4, 8, 7, 8, 5, 7, 8, 7, 4, 6, 2, 7, 7, 8, 7, 4, 5, 6, 4, 6, 4, 6, 4, 6, 6]

cp's OEIS Frontend

A262403 Number of ways to write pi(T(n)) = pi(T(k)) + pi(T(m)) with 1 < k < m < n, where T(x) is the triangular number x*(x+1)/2, and pi(x) is the number of primes not exceeding x.

Table of values

List of values

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

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

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