A075573 - cp's OEIS frontend

A075573 a(1)=1; a(n) is the smallest positive number not occurring earlier, with different parity from a(n-1), such that sum of any subsequence of two or more consecutive terms is composite.

n	a(n)
1	1
2	8
3	7
4	18
5	15
6	6
7	3
8	36
9	21
10	30
11	9
12	16
13	5
14	44
15	25
16	24
17	27
18	60
19	39
20	42
21	33
22	66
23	69
24	26
25	37
26	48
27	57
28	12
29	51
30	14
31	49
32	84
33	63
34	90
35	99
36	120
37	81
38	126
39	29
40	4
41	95
42	22
43	93
44	102
45	129
46	72
47	75
48	132
49	111
50	108
51	45
52	96
53	141
54	114
55	105
56	150
57	171
58	54
59	135
60	168
61	123
62	78
63	177
64	144
65	117

[1, 8, 7, 18, 15, 6, 3, 36, 21, 30, 9, 16, 5, 44, 25, 24, 27, 60, 39, 42, 33, 66, 69, 26, 37, 48, 57, 12, 51, 14, 49, 84, 63, 90, 99, 120, 81, 126, 29, 4, 95, 22, 93, 102, 129, 72, 75, 132, 111, 108, 45, 96, 141, 114, 105, 150, 171, 54, 135, 168, 123, 78, 177, 144, 117]

cp's OEIS Frontend

A075573 a(1)=1; a(n) is the smallest positive number not occurring earlier, with different parity from a(n-1), such that sum of any subsequence of two or more consecutive terms is composite.

Table of values

List of values

n	a(n)
1	1
2	8
3	7
4	18
5	15
6	6
7	3
8	36
9	21
10	30
11	9
12	16
13	5
14	44
15	25
16	24
17	27
18	60
19	39
20	42
21	33
22	66
23	69
24	26
25	37
26	48
27	57
28	12
29	51
30	14
31	49
32	84
33	63
34	90
35	99
36	120
37	81
38	126
39	29
40	4
41	95
42	22
43	93
44	102
45	129
46	72
47	75
48	132
49	111
50	108
51	45
52	96
53	141
54	114
55	105
56	150
57	171
58	54
59	135
60	168
61	123
62	78
63	177
64	144
65	117

n	a(n)
1	1
2	8
3	7
4	18
5	15
6	6
7	3
8	36
9	21
10	30
11	9
12	16
13	5
14	44
15	25
16	24
17	27
18	60
19	39
20	42
21	33
22	66
23	69
24	26
25	37
26	48
27	57
28	12
29	51
30	14
31	49
32	84
33	63
34	90
35	99
36	120
37	81
38	126
39	29
40	4
41	95
42	22
43	93
44	102
45	129
46	72
47	75
48	132
49	111
50	108
51	45
52	96
53	141
54	114
55	105
56	150
57	171
58	54
59	135
60	168
61	123
62	78
63	177
64	144
65	117

n	a(n)
1	1
2	8
3	7
4	18
5	15
6	6
7	3
8	36
9	21
10	30
11	9
12	16
13	5
14	44
15	25
16	24
17	27
18	60
19	39
20	42
21	33
22	66
23	69
24	26
25	37
26	48
27	57
28	12
29	51
30	14
31	49
32	84
33	63
34	90
35	99
36	120
37	81
38	126
39	29
40	4
41	95
42	22
43	93
44	102
45	129
46	72
47	75
48	132
49	111
50	108
51	45
52	96
53	141
54	114
55	105
56	150
57	171
58	54
59	135
60	168
61	123
62	78
63	177
64	144
65	117