A256420 - cp's OEIS frontend

A256420 a(n) = 2n unless n is prime, in which case a(n) = first term not yet present in the sequence.

n	a(n)
1	2
2	1
3	3
4	8
5	4
6	12
7	5
8	16
9	18
10	20
11	6
12	24
13	7
14	28
15	30
16	32
17	9
18	36
19	10
20	40
21	42
22	44
23	11
24	48
25	50
26	52
27	54
28	56
29	13
30	60
31	14
32	64
33	66
34	68
35	70
36	72
37	15
38	76
39	78
40	80
41	17
42	84
43	19
44	88
45	90
46	92
47	21
48	96
49	98
50	100
51	102
52	104
53	22
54	108
55	110
56	112
57	114
58	116
59	23
60	120

[2, 1, 3, 8, 4, 12, 5, 16, 18, 20, 6, 24, 7, 28, 30, 32, 9, 36, 10, 40, 42, 44, 11, 48, 50, 52, 54, 56, 13, 60, 14, 64, 66, 68, 70, 72, 15, 76, 78, 80, 17, 84, 19, 88, 90, 92, 21, 96, 98, 100, 102, 104, 22, 108, 110, 112, 114, 116, 23, 120]

cp's OEIS Frontend

A256420 a(n) = 2n unless n is prime, in which case a(n) = first term not yet present in the sequence.

Table of values

List of values

n	a(n)
1	2
2	1
3	3
4	8
5	4
6	12
7	5
8	16
9	18
10	20
11	6
12	24
13	7
14	28
15	30
16	32
17	9
18	36
19	10
20	40
21	42
22	44
23	11
24	48
25	50
26	52
27	54
28	56
29	13
30	60
31	14
32	64
33	66
34	68
35	70
36	72
37	15
38	76
39	78
40	80
41	17
42	84
43	19
44	88
45	90
46	92
47	21
48	96
49	98
50	100
51	102
52	104
53	22
54	108
55	110
56	112
57	114
58	116
59	23
60	120

n	a(n)
1	2
2	1
3	3
4	8
5	4
6	12
7	5
8	16
9	18
10	20
11	6
12	24
13	7
14	28
15	30
16	32
17	9
18	36
19	10
20	40
21	42
22	44
23	11
24	48
25	50
26	52
27	54
28	56
29	13
30	60
31	14
32	64
33	66
34	68
35	70
36	72
37	15
38	76
39	78
40	80
41	17
42	84
43	19
44	88
45	90
46	92
47	21
48	96
49	98
50	100
51	102
52	104
53	22
54	108
55	110
56	112
57	114
58	116
59	23
60	120

n	a(n)
1	2
2	1
3	3
4	8
5	4
6	12
7	5
8	16
9	18
10	20
11	6
12	24
13	7
14	28
15	30
16	32
17	9
18	36
19	10
20	40
21	42
22	44
23	11
24	48
25	50
26	52
27	54
28	56
29	13
30	60
31	14
32	64
33	66
34	68
35	70
36	72
37	15
38	76
39	78
40	80
41	17
42	84
43	19
44	88
45	90
46	92
47	21
48	96
49	98
50	100
51	102
52	104
53	22
54	108
55	110
56	112
57	114
58	116
59	23
60	120