A379440 - cp's OEIS frontend

A379440 a(1) = 1, a(2) = 2, for a(n) > 2, a(n) is the smallest unused positive number that shares a factor with a(n-1) such that the exponents of each distinct prime factor of a(n) differ by one from those of the same prime factors of a(n-1).

n	a(n)
1	1
2	2
3	4
4	6
5	9
6	3
7	18
8	12
9	8
10	16
11	24
12	20
13	14
14	44
15	10
16	25
17	5
18	50
19	15
20	63
21	27
22	45
23	21
24	49
25	7
26	98
27	28
28	22
29	52
30	30
31	36
32	26
33	60
34	34
35	76
36	40
37	48
38	32
39	64
40	96
41	80
42	56
43	68
44	38
45	84
46	46
47	116
48	42
49	92
50	58
51	124
52	66
53	117
54	33
55	90
56	39
57	99
58	51
59	126
60	57
61	153
62	54
63	81
64	135
65	162
66	108
67	62
68	132
69	70
70	75
71	35
72	147
73	77
74	121
75	11
76	242
77	55
78	150
79	65
80	169
81	13
82	338
83	91
84	245
85	119
86	289
87	17

[1, 2, 4, 6, 9, 3, 18, 12, 8, 16, 24, 20, 14, 44, 10, 25, 5, 50, 15, 63, 27, 45, 21, 49, 7, 98, 28, 22, 52, 30, 36, 26, 60, 34, 76, 40, 48, 32, 64, 96, 80, 56, 68, 38, 84, 46, 116, 42, 92, 58, 124, 66, 117, 33, 90, 39, 99, 51, 126, 57, 153, 54, 81, 135, 162, 108, 62, 132, 70, 75, 35, 147, 77, 121, 11, 242, 55, 150, 65, 169, 13, 338, 91, 245, 119, 289, 17]

cp's OEIS Frontend

A379440 a(1) = 1, a(2) = 2, for a(n) > 2, a(n) is the smallest unused positive number that shares a factor with a(n-1) such that the exponents of each distinct prime factor of a(n) differ by one from those of the same prime factors of a(n-1).

Table of values

List of values

n	a(n)
1	1
2	2
3	4
4	6
5	9
6	3
7	18
8	12
9	8
10	16
11	24
12	20
13	14
14	44
15	10
16	25
17	5
18	50
19	15
20	63
21	27
22	45
23	21
24	49
25	7
26	98
27	28
28	22
29	52
30	30
31	36
32	26
33	60
34	34
35	76
36	40
37	48
38	32
39	64
40	96
41	80
42	56
43	68
44	38
45	84
46	46
47	116
48	42
49	92
50	58
51	124
52	66
53	117
54	33
55	90
56	39
57	99
58	51
59	126
60	57
61	153
62	54
63	81
64	135
65	162
66	108
67	62
68	132
69	70
70	75
71	35
72	147
73	77
74	121
75	11
76	242
77	55
78	150
79	65
80	169
81	13
82	338
83	91
84	245
85	119
86	289
87	17

n	a(n)
1	1
2	2
3	4
4	6
5	9
6	3
7	18
8	12
9	8
10	16
11	24
12	20
13	14
14	44
15	10
16	25
17	5
18	50
19	15
20	63
21	27
22	45
23	21
24	49
25	7
26	98
27	28
28	22
29	52
30	30
31	36
32	26
33	60
34	34
35	76
36	40
37	48
38	32
39	64
40	96
41	80
42	56
43	68
44	38
45	84
46	46
47	116
48	42
49	92
50	58
51	124
52	66
53	117
54	33
55	90
56	39
57	99
58	51
59	126
60	57
61	153
62	54
63	81
64	135
65	162
66	108
67	62
68	132
69	70
70	75
71	35
72	147
73	77
74	121
75	11
76	242
77	55
78	150
79	65
80	169
81	13
82	338
83	91
84	245
85	119
86	289
87	17

n	a(n)
1	1
2	2
3	4
4	6
5	9
6	3
7	18
8	12
9	8
10	16
11	24
12	20
13	14
14	44
15	10
16	25
17	5
18	50
19	15
20	63
21	27
22	45
23	21
24	49
25	7
26	98
27	28
28	22
29	52
30	30
31	36
32	26
33	60
34	34
35	76
36	40
37	48
38	32
39	64
40	96
41	80
42	56
43	68
44	38
45	84
46	46
47	116
48	42
49	92
50	58
51	124
52	66
53	117
54	33
55	90
56	39
57	99
58	51
59	126
60	57
61	153
62	54
63	81
64	135
65	162
66	108
67	62
68	132
69	70
70	75
71	35
72	147
73	77
74	121
75	11
76	242
77	55
78	150
79	65
80	169
81	13
82	338
83	91
84	245
85	119
86	289
87	17