A087403 - cp's OEIS frontend

A087403 a(n) = smallest prime of the form 10*K(n) + 1, where K is a number obtained by concatenation of n with itself, or 0 if no such prime exists.

n	a(n)
1	11
2	2221
3	31
4	41
5	555555555551
6	61
7	71
8	881
9	991
10	101
11	1111111111111111111
12	1212121
13	131
14	14141414141
15	151
16	1616161
17	1717171717171717171717171717171
18	181
19	191
20	20201
21	211

[11, 2221, 31, 41, 555555555551, 61, 71, 881, 991, 101, 1111111111111111111, 1212121, 131, 14141414141, 151, 1616161, 1717171717171717171717171717171, 181, 191, 20201, 211]

cp's OEIS Frontend

A087403 a(n) = smallest prime of the form 10*K(n) + 1, where K is a number obtained by concatenation of n with itself, or 0 if no such prime exists.

Table of values

List of values