A068684 Primes obtained as a concatenation p,q,p where p and q are successive primes and p<q.

353, 131713, 171917, 192319, 293129, 374137, 434743, 596159, 677167, 139149139, 163167163, 179181179, 223227223, 229233229, 269271269, 281283281, 347349347, 379383379, 547557547, 683691683, 761769761, 857859857, 863877863

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Example

171917 is a prime which is the concatenation of 17, 19 and 17.

Prog

(PARI) f(n)=prime(n)*(10^(ceil(log(prime(n+1))/log(10))+ceil(log(prime(n))/log(10))))+ prime(n+1)*10^ceil(log(prime(n))/log(10))+prime(n); for(n=1, 300, if(isprime(f(n))==1, print1(f(n), ", ")))

Crossrefs

Cf. A068683, A078350.

Sequence in context: A126113 A282998 A213470 * A270782 A251127 A176197

Adjacent sequences: A068681 A068682 A068683 * A068685 A068686 A068687

Keyword

base,nonn

Author

Amarnath Murthy, Mar 02 2002

Extensions

More terms from Benoit Cloitre, Mar 21 2002

Status

approved