A228425 - cp's OEIS frontend

A228425 Number of ways to write n = x + y (x, y > 0) with x*(x+1)/2 + y^2 prime.

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

[0, 1, 1, 2, 2, 1, 3, 2, 2, 3, 2, 4, 4, 2, 2, 3, 6, 1, 5, 2, 3, 4, 3, 5, 1, 6, 4, 5, 2, 5, 8, 5, 6, 5, 3, 6, 10, 5, 5, 9, 8, 6, 13, 3, 5, 12, 9, 6, 4, 6, 7, 18, 5, 7, 4, 7, 14, 6, 11, 7, 16, 6, 7, 13, 6, 9, 13, 8, 6, 11, 7, 15, 14, 6, 11, 11, 6, 15, 12, 9, 6, 20, 9, 5, 20, 9, 8, 14, 15, 8, 9, 18, 7, 15, 6, 16, 17, 9, 10, 7]

cp's OEIS Frontend

A228425 Number of ways to write n = x + y (x, y > 0) with x*(x+1)/2 + y^2 prime.

Table of values

List of values

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

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

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