A034819 Concatenations C1 and C2 and C3 and C4 are all prime (see the comment lines).

51, 63, 123, 597, 687, 987, 4429, 12237, 18291, 20013, 29953, 31863, 34653, 48023, 52703, 57147, 59337, 62097, 66727, 71733, 81263, 86589, 101211, 105501, 118617, 121397, 134013, 146191, 147151, 155937, 174723, 175797, 179191, 180189, 205287

Offset

0,1

Comments

C1 = 'nextprime(n) followed by n'

C2 = 'n followed by nextprime(n)'

C3 = 'prevprime(n) followed by n'

C4 = 'n followed by prevprime(n)'

Links

Table of n, a(n) for n=0..34.

Example

n=105501 -> next prime is 105503, previous prime is 105499, thus '105503105501' and '105501105503' and '105501105499' and '105499105501' are all four primes.

Crossrefs

Cf. A034808-A034821.

Sequence in context: A050701 A206525 A216055 * A335346 A118147 A015863

Adjacent sequences: A034816 A034817 A034818 * A034820 A034821 A034822

Keyword

nonn,base

Author

Patrick De Geest, Oct 15 1998

Status

approved