A068683 Primes formed by the concatenation p,q,p where p and q are successive primes and p>q.

757, 131113, 171317, 231923, 312931, 474347, 978997, 10197101, 107103107, 127113127, 139137139, 151149151, 167163167, 367359367, 421419421, 433431433, 461457461, 617613617, 643641643, 701691701, 863859863, 911907911, 991983991

Offset

1,1

Links

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

Example

171317 is a prime which is the concatenation of 17, 13 and 17.

Mathematica

Select[FromDigits[Flatten[IntegerDigits/@#]]&/@({Last[#], First[#], Last[#]} &/@Partition[Prime[Range[200]], 2, 1]), PrimeQ] (* Harvey P. Dale, Oct 25 2011 *)

Crossrefs

Sequence in context: A173507 A101833 A261858 * A221340 A290738 A104336

Adjacent sequences: A068680 A068681 A068682 * A068684 A068685 A068686

Keyword

base,nonn

Author

Amarnath Murthy, Mar 02 2002

Extensions

More terms from Sascha Kurz, Mar 26 2002

Status

approved