A034816 Concatenations C1 and C2 are both prime (see the comment lines).

9, 51, 63, 117, 123, 157, 183, 213, 217, 219, 257, 263, 321, 327, 333, 423, 441, 473, 541, 597, 621, 687, 693, 723, 777, 879, 909, 987, 1101, 1143, 1187, 1387, 1459, 1551, 1887, 2127, 2179, 2193, 2817, 3197, 3339, 3513, 3633, 4029, 4209, 4429, 4529, 4557

Offset

0,1

Comments

C1 = 'prevprime(n) followed by n'

C2 = 'n followed by nextprime(n)'

Links

Table of n, a(n) for n=0..47.

Example

n=1551 -> previous prime is 1549, next prime is 1553, thus '15491551' and '15511553' are both primes.

Crossrefs

Cf. A034808-A034821.

Sequence in context: A002462 A210061 A034814 * A140381 A330805 A282877

Adjacent sequences: A034813 A034814 A034815 * A034817 A034818 A034819

Keyword

nonn,base

Author

Patrick De Geest, Oct 15 1998

Status

approved