A306803 - cp's OEIS frontend

A306803 An irregular fractal sequence: underline a(n) iff [a(n-1) + a(n)] is prime; all underlined terms rebuild the starting sequence.

n	a(n)
1	0
2	1
3	3
4	0
5	4
6	1
7	5
8	7
9	2
10	3
11	0
12	6
13	8
14	10
15	11
16	9
17	4
18	1
19	13
20	12
21	5
22	15
23	17
24	16
25	7
26	14
27	18
28	20
29	19
30	21
31	2
32	3
33	0
34	22
35	23
36	6
37	24
38	25
39	26
40	28
41	27
42	29
43	8
44	30
45	32
46	31
47	10
48	34
49	35
50	33
51	36
52	11
53	37
54	38
55	9
56	4
57	1
58	39
59	41
60	40
61	13
62	42
63	43
64	44
65	46
66	45
67	47
68	12
69	5
70	49
71	50
72	48
73	51
74	53
75	52
76	15
77	54
78	17
79	55
80	16
81	7
82	56
83	58
84	57
85	14
86	60
87	59
88	61
89	18
90	62

[0, 1, 3, 0, 4, 1, 5, 7, 2, 3, 0, 6, 8, 10, 11, 9, 4, 1, 13, 12, 5, 15, 17, 16, 7, 14, 18, 20, 19, 21, 2, 3, 0, 22, 23, 6, 24, 25, 26, 28, 27, 29, 8, 30, 32, 31, 10, 34, 35, 33, 36, 11, 37, 38, 9, 4, 1, 39, 41, 40, 13, 42, 43, 44, 46, 45, 47, 12, 5, 49, 50, 48, 51, 53, 52, 15, 54, 17, 55, 16, 7, 56, 58, 57, 14, 60, 59, 61, 18, 62]

cp's OEIS Frontend

A306803 An irregular fractal sequence: underline a(n) iff [a(n-1) + a(n)] is prime; all underlined terms rebuild the starting sequence.

Table of values

List of values

n	a(n)
1	0
2	1
3	3
4	0
5	4
6	1
7	5
8	7
9	2
10	3
11	0
12	6
13	8
14	10
15	11
16	9
17	4
18	1
19	13
20	12
21	5
22	15
23	17
24	16
25	7
26	14
27	18
28	20
29	19
30	21
31	2
32	3
33	0
34	22
35	23
36	6
37	24
38	25
39	26
40	28
41	27
42	29
43	8
44	30
45	32
46	31
47	10
48	34
49	35
50	33
51	36
52	11
53	37
54	38
55	9
56	4
57	1
58	39
59	41
60	40
61	13
62	42
63	43
64	44
65	46
66	45
67	47
68	12
69	5
70	49
71	50
72	48
73	51
74	53
75	52
76	15
77	54
78	17
79	55
80	16
81	7
82	56
83	58
84	57
85	14
86	60
87	59
88	61
89	18
90	62

n	a(n)
1	0
2	1
3	3
4	0
5	4
6	1
7	5
8	7
9	2
10	3
11	0
12	6
13	8
14	10
15	11
16	9
17	4
18	1
19	13
20	12
21	5
22	15
23	17
24	16
25	7
26	14
27	18
28	20
29	19
30	21
31	2
32	3
33	0
34	22
35	23
36	6
37	24
38	25
39	26
40	28
41	27
42	29
43	8
44	30
45	32
46	31
47	10
48	34
49	35
50	33
51	36
52	11
53	37
54	38
55	9
56	4
57	1
58	39
59	41
60	40
61	13
62	42
63	43
64	44
65	46
66	45
67	47
68	12
69	5
70	49
71	50
72	48
73	51
74	53
75	52
76	15
77	54
78	17
79	55
80	16
81	7
82	56
83	58
84	57
85	14
86	60
87	59
88	61
89	18
90	62

n	a(n)
1	0
2	1
3	3
4	0
5	4
6	1
7	5
8	7
9	2
10	3
11	0
12	6
13	8
14	10
15	11
16	9
17	4
18	1
19	13
20	12
21	5
22	15
23	17
24	16
25	7
26	14
27	18
28	20
29	19
30	21
31	2
32	3
33	0
34	22
35	23
36	6
37	24
38	25
39	26
40	28
41	27
42	29
43	8
44	30
45	32
46	31
47	10
48	34
49	35
50	33
51	36
52	11
53	37
54	38
55	9
56	4
57	1
58	39
59	41
60	40
61	13
62	42
63	43
64	44
65	46
66	45
67	47
68	12
69	5
70	49
71	50
72	48
73	51
74	53
75	52
76	15
77	54
78	17
79	55
80	16
81	7
82	56
83	58
84	57
85	14
86	60
87	59
88	61
89	18
90	62