A107393 - cp's OEIS frontend

A107393 a(n) = -1 if n is a prime, else a(n) = 1 if n is the sum of three odd primes, else a(n) = 2 if n is the sum of two primes, else a(n) = 0.

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

[0, 0, -1, -1, 2, -1, 2, -1, 2, 1, 2, -1, 2, -1, 2, 1, 2, -1, 2, -1, 2, 1, 2, -1, 2, 1, 2, 1, 2, -1, 2, -1, 2, 1, 2, 1, 2, -1, 2, 1, 2, -1, 2, -1, 2, 1, 2, -1, 2, 1, 2, 1, 2, -1, 2, 1, 2, 1, 2, -1, 2, -1, 2, 1, 2, 1, 2, -1, 2, 1, 2, -1, 2, -1, 2, 1, 2, 1, 2, -1, 2, 1, 2, -1, 2, 1, 2, 1, 2, -1, 2, 1, 2, 1, 2, 1, 2, -1, 2, 1, 2]

cp's OEIS Frontend

A107393 a(n) = -1 if n is a prime, else a(n) = 1 if n is the sum of three odd primes, else a(n) = 2 if n is the sum of two primes, else a(n) = 0.

Table of values

List of values

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

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

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