A102499 - OEIS

%I #10 Dec 17 2023 16:12:05

%S 313133,323233,328283,329293,338383,343433,349493,350503,352523,

%T 356563,364643,367673,380803,383833,392923,394943,395953,397973,

%U 3100010003,3100310033,3102410243,3102510253,3102810283,3103910393,3104610463

%N Primes of the concatenated form 3nn3.

%e 313133 is prime and of the form 3nn3 for n=13.

%e 3100010003 is prime and of the form 3nn3 for n=1000.

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

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

%K easy,nonn,base

%O 1,1

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