A297121 - cp's OEIS frontend

A297121 Self-describing sequence: sequence starts with a(1) = 2 and a(n) is chosen to be the smallest positive number not already in the sequence such that the assertion "sequence gives the positions of the even digits when the sequence is read as a string of digits" is true.

n	a(n)
1	2
2	4
3	1
4	6
5	7
6	8
7	20
8	10
9	12
10	14
11	16
12	18
13	22
14	24
15	26
16	28
17	30
18	32
19	34
20	36
21	38
22	40
23	42
24	44
25	46
26	48
27	50
28	52
29	54
30	56
31	58
32	60
33	62
34	64
35	66
36	68
37	70
38	72
39	74
40	76
41	78
42	80
43	82
44	84
45	86
46	88
47	90
48	92
49	94
50	96
51	98
52	100
53	21
54	19
55	23
56	25
57	37
58	39
59	41
60	43
61	45
62	57
63	59
64	61
65	63
66	65
67	77
68	79
69	81
70	83
71	85
72	99
73	104
74	106
75	112

[2, 4, 1, 6, 7, 8, 20, 10, 12, 14, 16, 18, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 21, 19, 23, 25, 37, 39, 41, 43, 45, 57, 59, 61, 63, 65, 77, 79, 81, 83, 85, 99, 104, 106, 112]

cp's OEIS Frontend

A297121 Self-describing sequence: sequence starts with a(1) = 2 and a(n) is chosen to be the smallest positive number not already in the sequence such that the assertion "sequence gives the positions of the even digits when the sequence is read as a string of digits" is true.

Table of values

List of values

n	a(n)
1	2
2	4
3	1
4	6
5	7
6	8
7	20
8	10
9	12
10	14
11	16
12	18
13	22
14	24
15	26
16	28
17	30
18	32
19	34
20	36
21	38
22	40
23	42
24	44
25	46
26	48
27	50
28	52
29	54
30	56
31	58
32	60
33	62
34	64
35	66
36	68
37	70
38	72
39	74
40	76
41	78
42	80
43	82
44	84
45	86
46	88
47	90
48	92
49	94
50	96
51	98
52	100
53	21
54	19
55	23
56	25
57	37
58	39
59	41
60	43
61	45
62	57
63	59
64	61
65	63
66	65
67	77
68	79
69	81
70	83
71	85
72	99
73	104
74	106
75	112

n	a(n)
1	2
2	4
3	1
4	6
5	7
6	8
7	20
8	10
9	12
10	14
11	16
12	18
13	22
14	24
15	26
16	28
17	30
18	32
19	34
20	36
21	38
22	40
23	42
24	44
25	46
26	48
27	50
28	52
29	54
30	56
31	58
32	60
33	62
34	64
35	66
36	68
37	70
38	72
39	74
40	76
41	78
42	80
43	82
44	84
45	86
46	88
47	90
48	92
49	94
50	96
51	98
52	100
53	21
54	19
55	23
56	25
57	37
58	39
59	41
60	43
61	45
62	57
63	59
64	61
65	63
66	65
67	77
68	79
69	81
70	83
71	85
72	99
73	104
74	106
75	112

n	a(n)
1	2
2	4
3	1
4	6
5	7
6	8
7	20
8	10
9	12
10	14
11	16
12	18
13	22
14	24
15	26
16	28
17	30
18	32
19	34
20	36
21	38
22	40
23	42
24	44
25	46
26	48
27	50
28	52
29	54
30	56
31	58
32	60
33	62
34	64
35	66
36	68
37	70
38	72
39	74
40	76
41	78
42	80
43	82
44	84
45	86
46	88
47	90
48	92
49	94
50	96
51	98
52	100
53	21
54	19
55	23
56	25
57	37
58	39
59	41
60	43
61	45
62	57
63	59
64	61
65	63
66	65
67	77
68	79
69	81
70	83
71	85
72	99
73	104
74	106
75	112