A103507 - cp's OEIS frontend

A103507 a(n) = Least i > 1, such that 2n+1 = 2*A000040(i)+A000040(k) for some k>1, 0 if no such i exists.

n	a(n)
1	0
2	0
3	0
4	2
5	2
6	2
7	3
8	2
9	2
10	3
11	2
12	2
13	3
14	2
15	4
16	3
17	2
18	2
19	3
20	3
21	2
22	4
23	2
24	2
25	3
26	2
27	4
28	3
29	2
30	4
31	3
32	2
33	2
34	3
35	3
36	2
37	4
38	2
39	2
40	3
41	3
42	2
43	4
44	2
45	8
46	3
47	2
48	4
49	3
50	5
51	2
52	5
53	2
54	2
55	3
56	2
57	2
58	3
59	2
60	4
61	3
62	5
63	4
64	5
65	5
66	2
67	5
68	2
69	6
70	3
71	2
72	2
73	3
74	3
75	4
76	4
77	2
78	2
79	3
80	3
81	2
82	4
83	3
84	2
85	4
86	2
87	6
88	3
89	2
90	4
91	3
92	2
93	2
94	3
95	3
96	4
97	4
98	2
99	2
100	3
101	2
102	2
103	3
104	3
105	4
106	4
107	5
108	2

[0, 0, 0, 2, 2, 2, 3, 2, 2, 3, 2, 2, 3, 2, 4, 3, 2, 2, 3, 3, 2, 4, 2, 2, 3, 2, 4, 3, 2, 4, 3, 2, 2, 3, 3, 2, 4, 2, 2, 3, 3, 2, 4, 2, 8, 3, 2, 4, 3, 5, 2, 5, 2, 2, 3, 2, 2, 3, 2, 4, 3, 5, 4, 5, 5, 2, 5, 2, 6, 3, 2, 2, 3, 3, 4, 4, 2, 2, 3, 3, 2, 4, 3, 2, 4, 2, 6, 3, 2, 4, 3, 2, 2, 3, 3, 4, 4, 2, 2, 3, 2, 2, 3, 3, 4, 4, 5, 2]

cp's OEIS Frontend

A103507 a(n) = Least i > 1, such that 2n+1 = 2*A000040(i)+A000040(k) for some k>1, 0 if no such i exists.

Table of values

List of values

n	a(n)
1	0
2	0
3	0
4	2
5	2
6	2
7	3
8	2
9	2
10	3
11	2
12	2
13	3
14	2
15	4
16	3
17	2
18	2
19	3
20	3
21	2
22	4
23	2
24	2
25	3
26	2
27	4
28	3
29	2
30	4
31	3
32	2
33	2
34	3
35	3
36	2
37	4
38	2
39	2
40	3
41	3
42	2
43	4
44	2
45	8
46	3
47	2
48	4
49	3
50	5
51	2
52	5
53	2
54	2
55	3
56	2
57	2
58	3
59	2
60	4
61	3
62	5
63	4
64	5
65	5
66	2
67	5
68	2
69	6
70	3
71	2
72	2
73	3
74	3
75	4
76	4
77	2
78	2
79	3
80	3
81	2
82	4
83	3
84	2
85	4
86	2
87	6
88	3
89	2
90	4
91	3
92	2
93	2
94	3
95	3
96	4
97	4
98	2
99	2
100	3
101	2
102	2
103	3
104	3
105	4
106	4
107	5
108	2

n	a(n)
1	0
2	0
3	0
4	2
5	2
6	2
7	3
8	2
9	2
10	3
11	2
12	2
13	3
14	2
15	4
16	3
17	2
18	2
19	3
20	3
21	2
22	4
23	2
24	2
25	3
26	2
27	4
28	3
29	2
30	4
31	3
32	2
33	2
34	3
35	3
36	2
37	4
38	2
39	2
40	3
41	3
42	2
43	4
44	2
45	8
46	3
47	2
48	4
49	3
50	5
51	2
52	5
53	2
54	2
55	3
56	2
57	2
58	3
59	2
60	4
61	3
62	5
63	4
64	5
65	5
66	2
67	5
68	2
69	6
70	3
71	2
72	2
73	3
74	3
75	4
76	4
77	2
78	2
79	3
80	3
81	2
82	4
83	3
84	2
85	4
86	2
87	6
88	3
89	2
90	4
91	3
92	2
93	2
94	3
95	3
96	4
97	4
98	2
99	2
100	3
101	2
102	2
103	3
104	3
105	4
106	4
107	5
108	2

n	a(n)
1	0
2	0
3	0
4	2
5	2
6	2
7	3
8	2
9	2
10	3
11	2
12	2
13	3
14	2
15	4
16	3
17	2
18	2
19	3
20	3
21	2
22	4
23	2
24	2
25	3
26	2
27	4
28	3
29	2
30	4
31	3
32	2
33	2
34	3
35	3
36	2
37	4
38	2
39	2
40	3
41	3
42	2
43	4
44	2
45	8
46	3
47	2
48	4
49	3
50	5
51	2
52	5
53	2
54	2
55	3
56	2
57	2
58	3
59	2
60	4
61	3
62	5
63	4
64	5
65	5
66	2
67	5
68	2
69	6
70	3
71	2
72	2
73	3
74	3
75	4
76	4
77	2
78	2
79	3
80	3
81	2
82	4
83	3
84	2
85	4
86	2
87	6
88	3
89	2
90	4
91	3
92	2
93	2
94	3
95	3
96	4
97	4
98	2
99	2
100	3
101	2
102	2
103	3
104	3
105	4
106	4
107	5
108	2