A098548 - cp's OEIS frontend

A098548 a(n) = n if n <= 3, otherwise the smallest number > a(n-1) having at least one common factor with a(n-2) but none with a(n-1).

n	a(n)
1	1
2	2
3	3
4	4
5	9
6	10
7	21
8	22
9	27
10	28
11	33
12	34
13	39
14	40
15	51
16	52
17	57
18	58
19	63
20	64
21	69
22	70
23	81
24	82
25	87
26	88
27	93
28	94
29	99
30	100
31	111
32	112
33	117
34	118
35	123
36	124
37	129
38	130
39	141
40	142
41	147
42	148
43	153
44	154
45	159
46	160
47	171
48	172
49	177
50	178
51	183
52	184
53	189
54	190
55	201
56	202
57	207
58	208
59	213
60	214

[1, 2, 3, 4, 9, 10, 21, 22, 27, 28, 33, 34, 39, 40, 51, 52, 57, 58, 63, 64, 69, 70, 81, 82, 87, 88, 93, 94, 99, 100, 111, 112, 117, 118, 123, 124, 129, 130, 141, 142, 147, 148, 153, 154, 159, 160, 171, 172, 177, 178, 183, 184, 189, 190, 201, 202, 207, 208, 213, 214]

cp's OEIS Frontend

A098548 a(n) = n if n <= 3, otherwise the smallest number > a(n-1) having at least one common factor with a(n-2) but none with a(n-1).

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	9
6	10
7	21
8	22
9	27
10	28
11	33
12	34
13	39
14	40
15	51
16	52
17	57
18	58
19	63
20	64
21	69
22	70
23	81
24	82
25	87
26	88
27	93
28	94
29	99
30	100
31	111
32	112
33	117
34	118
35	123
36	124
37	129
38	130
39	141
40	142
41	147
42	148
43	153
44	154
45	159
46	160
47	171
48	172
49	177
50	178
51	183
52	184
53	189
54	190
55	201
56	202
57	207
58	208
59	213
60	214

n	a(n)
1	1
2	2
3	3
4	4
5	9
6	10
7	21
8	22
9	27
10	28
11	33
12	34
13	39
14	40
15	51
16	52
17	57
18	58
19	63
20	64
21	69
22	70
23	81
24	82
25	87
26	88
27	93
28	94
29	99
30	100
31	111
32	112
33	117
34	118
35	123
36	124
37	129
38	130
39	141
40	142
41	147
42	148
43	153
44	154
45	159
46	160
47	171
48	172
49	177
50	178
51	183
52	184
53	189
54	190
55	201
56	202
57	207
58	208
59	213
60	214

n	a(n)
1	1
2	2
3	3
4	4
5	9
6	10
7	21
8	22
9	27
10	28
11	33
12	34
13	39
14	40
15	51
16	52
17	57
18	58
19	63
20	64
21	69
22	70
23	81
24	82
25	87
26	88
27	93
28	94
29	99
30	100
31	111
32	112
33	117
34	118
35	123
36	124
37	129
38	130
39	141
40	142
41	147
42	148
43	153
44	154
45	159
46	160
47	171
48	172
49	177
50	178
51	183
52	184
53	189
54	190
55	201
56	202
57	207
58	208
59	213
60	214