A306808 - cp's OEIS frontend

A306808 An irregular fractal sequence: underline a(n) iff the sum [a(n-1) + a(n)] is a palindrome; all underlined terms rebuild the starting sequence.

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

[1, 9, 3, 1, 11, 2, 9, 4, 3, 1, 12, 5, 7, 6, 8, 10, 13, 14, 15, 16, 18, 17, 19, 20, 21, 22, 11, 23, 24, 25, 26, 27, 29, 28, 30, 31, 2, 9, 32, 33, 34, 35, 36, 37, 38, 40, 4, 3, 1, 39, 41, 42, 43, 12, 44, 45, 46, 47, 48, 49, 51, 52, 50, 5, 53, 54, 55, 57, 56, 58, 59, 7, 60, 6, 61, 62, 63, 64, 65, 67, 66, 68, 69, 8, 70, 72, 71, 73, 74]

cp's OEIS Frontend

A306808 An irregular fractal sequence: underline a(n) iff the sum [a(n-1) + a(n)] is a palindrome; all underlined terms rebuild the starting sequence.

Table of values

List of values

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

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

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