A064419 - cp's OEIS frontend

A064419 a(n) = n for n <= 5; for n > 5, a(n) = smallest number not already used such that gcd(a(n), a(n-1)) >= 5.

n	a(n)
1	1
2	2
3	3
4	4
5	5
6	10
7	15
8	20
9	25
10	30
11	6
12	12
13	18
14	9
15	27
16	36
17	24
18	8
19	16
20	32
21	40
22	35
23	7
24	14
25	21
26	28
27	42
28	48
29	54
30	45
31	50
32	55
33	11
34	22
35	33
36	44
37	66
38	60
39	65
40	13
41	26
42	39
43	52
44	78
45	72
46	56
47	49
48	63
49	70
50	75
51	80
52	64
53	88
54	77
55	84
56	90
57	81
58	99
59	108
60	96
61	102
62	17
63	34
64	51
65	68
66	85
67	95
68	19
69	38
70	57
71	76
72	114
73	120

[1, 2, 3, 4, 5, 10, 15, 20, 25, 30, 6, 12, 18, 9, 27, 36, 24, 8, 16, 32, 40, 35, 7, 14, 21, 28, 42, 48, 54, 45, 50, 55, 11, 22, 33, 44, 66, 60, 65, 13, 26, 39, 52, 78, 72, 56, 49, 63, 70, 75, 80, 64, 88, 77, 84, 90, 81, 99, 108, 96, 102, 17, 34, 51, 68, 85, 95, 19, 38, 57, 76, 114, 120]

cp's OEIS Frontend

A064419 a(n) = n for n <= 5; for n > 5, a(n) = smallest number not already used such that gcd(a(n), a(n-1)) >= 5.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	5
6	10
7	15
8	20
9	25
10	30
11	6
12	12
13	18
14	9
15	27
16	36
17	24
18	8
19	16
20	32
21	40
22	35
23	7
24	14
25	21
26	28
27	42
28	48
29	54
30	45
31	50
32	55
33	11
34	22
35	33
36	44
37	66
38	60
39	65
40	13
41	26
42	39
43	52
44	78
45	72
46	56
47	49
48	63
49	70
50	75
51	80
52	64
53	88
54	77
55	84
56	90
57	81
58	99
59	108
60	96
61	102
62	17
63	34
64	51
65	68
66	85
67	95
68	19
69	38
70	57
71	76
72	114
73	120

n	a(n)
1	1
2	2
3	3
4	4
5	5
6	10
7	15
8	20
9	25
10	30
11	6
12	12
13	18
14	9
15	27
16	36
17	24
18	8
19	16
20	32
21	40
22	35
23	7
24	14
25	21
26	28
27	42
28	48
29	54
30	45
31	50
32	55
33	11
34	22
35	33
36	44
37	66
38	60
39	65
40	13
41	26
42	39
43	52
44	78
45	72
46	56
47	49
48	63
49	70
50	75
51	80
52	64
53	88
54	77
55	84
56	90
57	81
58	99
59	108
60	96
61	102
62	17
63	34
64	51
65	68
66	85
67	95
68	19
69	38
70	57
71	76
72	114
73	120

n	a(n)
1	1
2	2
3	3
4	4
5	5
6	10
7	15
8	20
9	25
10	30
11	6
12	12
13	18
14	9
15	27
16	36
17	24
18	8
19	16
20	32
21	40
22	35
23	7
24	14
25	21
26	28
27	42
28	48
29	54
30	45
31	50
32	55
33	11
34	22
35	33
36	44
37	66
38	60
39	65
40	13
41	26
42	39
43	52
44	78
45	72
46	56
47	49
48	63
49	70
50	75
51	80
52	64
53	88
54	77
55	84
56	90
57	81
58	99
59	108
60	96
61	102
62	17
63	34
64	51
65	68
66	85
67	95
68	19
69	38
70	57
71	76
72	114
73	120