A113475 - cp's OEIS frontend

A113475 a(1)=1 and a(n) for n>1 has the smallest positive value such that Sum_{i=1..n} a(i)^a(n-i+1) is semiprime (A001358).

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

[1, 3, 5, 2, 4, 2, 2, 4, 2, 4, 3, 2, 3, 4, 2, 2, 1, 1, 2, 1, 5, 1, 7, 1, 5, 4, 2, 2, 3, 3, 2, 11, 5, 10, 4, 2, 2, 6, 14, 4, 6, 2, 3, 9, 14, 10, 3, 3, 4, 2, 1, 5, 4, 16, 8, 9, 5, 8, 14, 6, 2, 2, 26, 8, 30, 4, 5, 1, 4, 2, 22, 36, 20, 2, 10, 2, 15, 3, 18, 6, 15]

cp's OEIS Frontend

A113475 a(1)=1 and a(n) for n>1 has the smallest positive value such that Sum_{i=1..n} a(i)^a(n-i+1) is semiprime (A001358).

Table of values

List of values

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

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

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