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%I
%S 5,7,101,151,353,727,757,929,10301,10601,12721,15551,16061,16661,
%T 18181,19391,19891,30403,30703,31013,31513,35353,36263,36563,38083,
%U 39293,72227,73237,76367,77377,77477,78487,79397,79997,93139,94649,94849
%N Palindromic primes that yield a prime when sandwiched between two 3's. (Prefixing and suffixing a -three' on both sides yields another pal prime).
%e 757 is a member as 37573 is also a prime.
%t s23Q[n_]:=Module[{idn=IntegerDigits[n]},idn==Reverse[idn]&&PrimeQ[ FromDigits[Join[{3},idn,{3}]]]]; Select[Prime[Range[10000]],s23Q] (* _Harvey P. Dale_, May 07 2011 *)
%Y Cf. A088269, A088271, A088272.
%K base,nonn
%O 1,1
%A _Amarnath Murthy_, Sep 28 2003
%E More terms from _David Wasserman_, Jul 28 2005
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