A251604 - cp's OEIS frontend

A251604 A Zumkeller-type sequence (cf. A098550): a(n) = n if n <= 3, otherwise the smallest number not occurring earlier having at least one common factor with a(n-2)+a(n-1), but none with a(n-1).

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	9
7	13
8	6
9	19
10	10
11	29
12	12
13	41
14	53
15	8
16	61
17	15
18	14
19	87
20	101
21	16
22	21
23	37
24	18
25	11
26	58
27	23
28	24
29	47
30	71
31	20
32	7
33	27
34	17
35	22
36	39
37	122
38	35
39	157
40	26
41	33
42	59
43	28
44	45
45	73
46	30
47	103
48	38
49	51
50	89
51	25
52	32
53	57
54	178
55	55
56	233
57	34
58	63
59	97
60	36
61	49
62	40
63	267
64	307
65	42

[1, 2, 3, 5, 4, 9, 13, 6, 19, 10, 29, 12, 41, 53, 8, 61, 15, 14, 87, 101, 16, 21, 37, 18, 11, 58, 23, 24, 47, 71, 20, 7, 27, 17, 22, 39, 122, 35, 157, 26, 33, 59, 28, 45, 73, 30, 103, 38, 51, 89, 25, 32, 57, 178, 55, 233, 34, 63, 97, 36, 49, 40, 267, 307, 42]

cp's OEIS Frontend

A251604 A Zumkeller-type sequence (cf. A098550): a(n) = n if n <= 3, otherwise the smallest number not occurring earlier having at least one common factor with a(n-2)+a(n-1), but none with a(n-1).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	9
7	13
8	6
9	19
10	10
11	29
12	12
13	41
14	53
15	8
16	61
17	15
18	14
19	87
20	101
21	16
22	21
23	37
24	18
25	11
26	58
27	23
28	24
29	47
30	71
31	20
32	7
33	27
34	17
35	22
36	39
37	122
38	35
39	157
40	26
41	33
42	59
43	28
44	45
45	73
46	30
47	103
48	38
49	51
50	89
51	25
52	32
53	57
54	178
55	55
56	233
57	34
58	63
59	97
60	36
61	49
62	40
63	267
64	307
65	42

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	9
7	13
8	6
9	19
10	10
11	29
12	12
13	41
14	53
15	8
16	61
17	15
18	14
19	87
20	101
21	16
22	21
23	37
24	18
25	11
26	58
27	23
28	24
29	47
30	71
31	20
32	7
33	27
34	17
35	22
36	39
37	122
38	35
39	157
40	26
41	33
42	59
43	28
44	45
45	73
46	30
47	103
48	38
49	51
50	89
51	25
52	32
53	57
54	178
55	55
56	233
57	34
58	63
59	97
60	36
61	49
62	40
63	267
64	307
65	42

n	a(n)
1	1
2	2
3	3
4	5
5	4
6	9
7	13
8	6
9	19
10	10
11	29
12	12
13	41
14	53
15	8
16	61
17	15
18	14
19	87
20	101
21	16
22	21
23	37
24	18
25	11
26	58
27	23
28	24
29	47
30	71
31	20
32	7
33	27
34	17
35	22
36	39
37	122
38	35
39	157
40	26
41	33
42	59
43	28
44	45
45	73
46	30
47	103
48	38
49	51
50	89
51	25
52	32
53	57
54	178
55	55
56	233
57	34
58	63
59	97
60	36
61	49
62	40
63	267
64	307
65	42