A064418 - cp's OEIS frontend

A064418 a(1) = 1, a(2) = 2, a(3) = 3, a(4) = 4; for n > 4, a(n) = smallest number not already used such that gcd(a(n), a(n-1)) >= 4.

n	a(n)
1	1
2	2
3	3
4	4
5	8
6	12
7	6
8	18
9	9
10	27
11	36
12	16
13	20
14	5
15	10
16	15
17	25
18	30
19	24
20	28
21	7
22	14
23	21
24	35
25	40
26	32
27	44
28	11
29	22
30	33
31	55
32	45
33	50
34	60
35	42
36	48
37	52
38	13
39	26
40	39
41	65
42	70
43	49
44	56
45	63
46	54
47	66
48	72
49	64
50	68
51	17
52	34
53	51
54	85
55	75
56	80
57	76
58	19
59	38
60	57
61	95
62	90
63	78
64	84
65	77
66	88
67	92
68	23
69	46
70	69
71	115
72	100
73	96

[1, 2, 3, 4, 8, 12, 6, 18, 9, 27, 36, 16, 20, 5, 10, 15, 25, 30, 24, 28, 7, 14, 21, 35, 40, 32, 44, 11, 22, 33, 55, 45, 50, 60, 42, 48, 52, 13, 26, 39, 65, 70, 49, 56, 63, 54, 66, 72, 64, 68, 17, 34, 51, 85, 75, 80, 76, 19, 38, 57, 95, 90, 78, 84, 77, 88, 92, 23, 46, 69, 115, 100, 96]

cp's OEIS Frontend

A064418 a(1) = 1, a(2) = 2, a(3) = 3, a(4) = 4; for n > 4, a(n) = smallest number not already used such that gcd(a(n), a(n-1)) >= 4.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	8
6	12
7	6
8	18
9	9
10	27
11	36
12	16
13	20
14	5
15	10
16	15
17	25
18	30
19	24
20	28
21	7
22	14
23	21
24	35
25	40
26	32
27	44
28	11
29	22
30	33
31	55
32	45
33	50
34	60
35	42
36	48
37	52
38	13
39	26
40	39
41	65
42	70
43	49
44	56
45	63
46	54
47	66
48	72
49	64
50	68
51	17
52	34
53	51
54	85
55	75
56	80
57	76
58	19
59	38
60	57
61	95
62	90
63	78
64	84
65	77
66	88
67	92
68	23
69	46
70	69
71	115
72	100
73	96

n	a(n)
1	1
2	2
3	3
4	4
5	8
6	12
7	6
8	18
9	9
10	27
11	36
12	16
13	20
14	5
15	10
16	15
17	25
18	30
19	24
20	28
21	7
22	14
23	21
24	35
25	40
26	32
27	44
28	11
29	22
30	33
31	55
32	45
33	50
34	60
35	42
36	48
37	52
38	13
39	26
40	39
41	65
42	70
43	49
44	56
45	63
46	54
47	66
48	72
49	64
50	68
51	17
52	34
53	51
54	85
55	75
56	80
57	76
58	19
59	38
60	57
61	95
62	90
63	78
64	84
65	77
66	88
67	92
68	23
69	46
70	69
71	115
72	100
73	96

n	a(n)
1	1
2	2
3	3
4	4
5	8
6	12
7	6
8	18
9	9
10	27
11	36
12	16
13	20
14	5
15	10
16	15
17	25
18	30
19	24
20	28
21	7
22	14
23	21
24	35
25	40
26	32
27	44
28	11
29	22
30	33
31	55
32	45
33	50
34	60
35	42
36	48
37	52
38	13
39	26
40	39
41	65
42	70
43	49
44	56
45	63
46	54
47	66
48	72
49	64
50	68
51	17
52	34
53	51
54	85
55	75
56	80
57	76
58	19
59	38
60	57
61	95
62	90
63	78
64	84
65	77
66	88
67	92
68	23
69	46
70	69
71	115
72	100
73	96