A303845 - cp's OEIS frontend

A303845 A fractal-like sequence: erasing all pairs of consecutive terms that produce a prime by concatenation leaves the sequence unchanged.

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

[1, 2, 3, 2, 4, 7, 5, 9, 3, 2, 4, 6, 13, 8, 11, 7, 5, 10, 19, 12, 17, 14, 23, 15, 31, 9, 3, 2, 4, 6, 16, 21, 18, 47, 13, 8, 20, 27, 22, 37, 11, 7, 5, 10, 24, 41, 19, 12, 25, 39, 26, 33, 17, 14, 28, 43, 23, 15, 29, 53, 31, 9, 3, 2, 4, 6, 16, 30, 49, 21, 18, 32, 51, 34, 57, 47, 13, 8, 20, 35, 59, 36, 71, 38, 63, 27, 22, 40, 73]

cp's OEIS Frontend

A303845 A fractal-like sequence: erasing all pairs of consecutive terms that produce a prime by concatenation leaves the sequence unchanged.

Table of values

List of values

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

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

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