A380978 - cp's OEIS frontend

A380978 Sequence of minimal Fermat witnesses for compositeness. a(n) is the least k such that the smallest composite number that is a Fermat pseudoprime to bases {a(i) : 1 <= i < n} is not a Fermat pseudoprime to base k.

n	a(n)
1	2
2	3
3	5
4	7
5	13
6	11
7	17
8	41
9	37
10	19
11	31
12	43
13	23
14	53
15	29
16	101
17	61
18	109
19	71
20	67
21	73
22	113
23	151
24	89
25	97
26	211
27	191
28	157
29	163
30	193
31	139
32	281
33	107
34	103
35	181
36	47
37	127
38	271
39	131
40	307
41	59
42	257
43	229
44	331
45	337
46	199
47	241
48	461
49	239
50	617
51	367
52	263
53	401
54	251
55	149
56	421
57	137
58	277

[2, 3, 5, 7, 13, 11, 17, 41, 37, 19, 31, 43, 23, 53, 29, 101, 61, 109, 71, 67, 73, 113, 151, 89, 97, 211, 191, 157, 163, 193, 139, 281, 107, 103, 181, 47, 127, 271, 131, 307, 59, 257, 229, 331, 337, 199, 241, 461, 239, 617, 367, 263, 401, 251, 149, 421, 137, 277]

cp's OEIS Frontend

A380978 Sequence of minimal Fermat witnesses for compositeness. a(n) is the least k such that the smallest composite number that is a Fermat pseudoprime to bases {a(i) : 1 <= i < n} is not a Fermat pseudoprime to base k.

Table of values

List of values

n	a(n)
1	2
2	3
3	5
4	7
5	13
6	11
7	17
8	41
9	37
10	19
11	31
12	43
13	23
14	53
15	29
16	101
17	61
18	109
19	71
20	67
21	73
22	113
23	151
24	89
25	97
26	211
27	191
28	157
29	163
30	193
31	139
32	281
33	107
34	103
35	181
36	47
37	127
38	271
39	131
40	307
41	59
42	257
43	229
44	331
45	337
46	199
47	241
48	461
49	239
50	617
51	367
52	263
53	401
54	251
55	149
56	421
57	137
58	277

n	a(n)
1	2
2	3
3	5
4	7
5	13
6	11
7	17
8	41
9	37
10	19
11	31
12	43
13	23
14	53
15	29
16	101
17	61
18	109
19	71
20	67
21	73
22	113
23	151
24	89
25	97
26	211
27	191
28	157
29	163
30	193
31	139
32	281
33	107
34	103
35	181
36	47
37	127
38	271
39	131
40	307
41	59
42	257
43	229
44	331
45	337
46	199
47	241
48	461
49	239
50	617
51	367
52	263
53	401
54	251
55	149
56	421
57	137
58	277

n	a(n)
1	2
2	3
3	5
4	7
5	13
6	11
7	17
8	41
9	37
10	19
11	31
12	43
13	23
14	53
15	29
16	101
17	61
18	109
19	71
20	67
21	73
22	113
23	151
24	89
25	97
26	211
27	191
28	157
29	163
30	193
31	139
32	281
33	107
34	103
35	181
36	47
37	127
38	271
39	131
40	307
41	59
42	257
43	229
44	331
45	337
46	199
47	241
48	461
49	239
50	617
51	367
52	263
53	401
54	251
55	149
56	421
57	137
58	277