A102499 Primes of the concatenated form 3nn3.

313133, 323233, 328283, 329293, 338383, 343433, 349493, 350503, 352523, 356563, 364643, 367673, 380803, 383833, 392923, 394943, 395953, 397973, 3100010003, 3100310033, 3102410243, 3102510253, 3102810283, 3103910393, 3104610463

Offset: 1

Author

Mark Hudson (mrmarkhudson(AT)hotmail.com), Jan 13 2005

Keywords

• easy
• nonn
• base

Examples

			313133 is prime and of the form 3nn3 for n=13.
3100010003 is prime and of the form 3nn3 for n=1000.
		

Crossrefs

Cf. A102896 for sequence of all numbers of form 3nn3. A102498 for the n values corresponding to the primes in this sequence.

Programs

Mathematica

mn[n_]:=Module[{idn=IntegerDigits[n]}, FromDigits[Join[{3},idn,idn,{3}]]]; Select[ mn/@ Range[ 1100],PrimeQ]  (* Harvey P. Dale, Feb 04 2011 *)