A263648 - cp's OEIS frontend

A263648 a(1)=4, a(2)=9: a(n) is the smallest semiprime not yet appearing in the sequence which is coprime to a(n-1) and not coprime to a(n-2).

n	a(n)
1	4
2	9
3	10
4	21
5	22
6	15
7	14
8	25
9	6
10	35
11	26
12	49
13	34
14	77
15	38
16	33
17	46
18	39
19	58
20	51
21	62
22	57
23	74
24	69
25	82
26	87
27	86
28	93
29	94
30	111
31	106
32	123
33	118
34	129
35	122
36	141
37	134
38	159
39	142
40	177
41	146
42	183
43	158
44	201
45	166
46	213
47	178
48	219
49	194
50	237
51	202
52	249
53	206
54	267
55	214
56	291
57	218
58	303
59	226
60	309

[4, 9, 10, 21, 22, 15, 14, 25, 6, 35, 26, 49, 34, 77, 38, 33, 46, 39, 58, 51, 62, 57, 74, 69, 82, 87, 86, 93, 94, 111, 106, 123, 118, 129, 122, 141, 134, 159, 142, 177, 146, 183, 158, 201, 166, 213, 178, 219, 194, 237, 202, 249, 206, 267, 214, 291, 218, 303, 226, 309]

cp's OEIS Frontend

A263648 a(1)=4, a(2)=9: a(n) is the smallest semiprime not yet appearing in the sequence which is coprime to a(n-1) and not coprime to a(n-2).

Table of values

List of values

n	a(n)
1	4
2	9
3	10
4	21
5	22
6	15
7	14
8	25
9	6
10	35
11	26
12	49
13	34
14	77
15	38
16	33
17	46
18	39
19	58
20	51
21	62
22	57
23	74
24	69
25	82
26	87
27	86
28	93
29	94
30	111
31	106
32	123
33	118
34	129
35	122
36	141
37	134
38	159
39	142
40	177
41	146
42	183
43	158
44	201
45	166
46	213
47	178
48	219
49	194
50	237
51	202
52	249
53	206
54	267
55	214
56	291
57	218
58	303
59	226
60	309

n	a(n)
1	4
2	9
3	10
4	21
5	22
6	15
7	14
8	25
9	6
10	35
11	26
12	49
13	34
14	77
15	38
16	33
17	46
18	39
19	58
20	51
21	62
22	57
23	74
24	69
25	82
26	87
27	86
28	93
29	94
30	111
31	106
32	123
33	118
34	129
35	122
36	141
37	134
38	159
39	142
40	177
41	146
42	183
43	158
44	201
45	166
46	213
47	178
48	219
49	194
50	237
51	202
52	249
53	206
54	267
55	214
56	291
57	218
58	303
59	226
60	309

n	a(n)
1	4
2	9
3	10
4	21
5	22
6	15
7	14
8	25
9	6
10	35
11	26
12	49
13	34
14	77
15	38
16	33
17	46
18	39
19	58
20	51
21	62
22	57
23	74
24	69
25	82
26	87
27	86
28	93
29	94
30	111
31	106
32	123
33	118
34	129
35	122
36	141
37	134
38	159
39	142
40	177
41	146
42	183
43	158
44	201
45	166
46	213
47	178
48	219
49	194
50	237
51	202
52	249
53	206
54	267
55	214
56	291
57	218
58	303
59	226
60	309