A363198 - cp's OEIS frontend

A363198 a(n) = n for n <= 3; for n >= 4, a(n) is the smallest positive integer that has not appeared previously in this sequence and shares a factor with a(n-1) + a(n-2) + a(n-3).

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	13
7	23
8	7
9	43
10	73
11	9
12	5
13	12
14	8
15	10
16	14
17	16
18	15
19	18
20	21
21	20
22	59
23	22
24	101
25	24
26	27
27	19
28	25
29	71
30	30
31	26
32	127
33	33
34	28
35	32
36	31
37	35
38	34
39	36
40	39
41	109
42	38
43	40
44	11
45	89
46	42
47	44
48	45
49	131
50	46
51	37
52	48
53	262
54	347
55	51
56	50
57	49
58	52
59	151
60	54
61	257
62	55
63	56
64	58
65	65

[1, 2, 3, 4, 6, 13, 23, 7, 43, 73, 9, 5, 12, 8, 10, 14, 16, 15, 18, 21, 20, 59, 22, 101, 24, 27, 19, 25, 71, 30, 26, 127, 33, 28, 32, 31, 35, 34, 36, 39, 109, 38, 40, 11, 89, 42, 44, 45, 131, 46, 37, 48, 262, 347, 51, 50, 49, 52, 151, 54, 257, 55, 56, 58, 65]

cp's OEIS Frontend

A363198 a(n) = n for n <= 3; for n >= 4, a(n) is the smallest positive integer that has not appeared previously in this sequence and shares a factor with a(n-1) + a(n-2) + a(n-3).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	13
7	23
8	7
9	43
10	73
11	9
12	5
13	12
14	8
15	10
16	14
17	16
18	15
19	18
20	21
21	20
22	59
23	22
24	101
25	24
26	27
27	19
28	25
29	71
30	30
31	26
32	127
33	33
34	28
35	32
36	31
37	35
38	34
39	36
40	39
41	109
42	38
43	40
44	11
45	89
46	42
47	44
48	45
49	131
50	46
51	37
52	48
53	262
54	347
55	51
56	50
57	49
58	52
59	151
60	54
61	257
62	55
63	56
64	58
65	65

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	13
7	23
8	7
9	43
10	73
11	9
12	5
13	12
14	8
15	10
16	14
17	16
18	15
19	18
20	21
21	20
22	59
23	22
24	101
25	24
26	27
27	19
28	25
29	71
30	30
31	26
32	127
33	33
34	28
35	32
36	31
37	35
38	34
39	36
40	39
41	109
42	38
43	40
44	11
45	89
46	42
47	44
48	45
49	131
50	46
51	37
52	48
53	262
54	347
55	51
56	50
57	49
58	52
59	151
60	54
61	257
62	55
63	56
64	58
65	65

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	13
7	23
8	7
9	43
10	73
11	9
12	5
13	12
14	8
15	10
16	14
17	16
18	15
19	18
20	21
21	20
22	59
23	22
24	101
25	24
26	27
27	19
28	25
29	71
30	30
31	26
32	127
33	33
34	28
35	32
36	31
37	35
38	34
39	36
40	39
41	109
42	38
43	40
44	11
45	89
46	42
47	44
48	45
49	131
50	46
51	37
52	48
53	262
54	347
55	51
56	50
57	49
58	52
59	151
60	54
61	257
62	55
63	56
64	58
65	65