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%I #19 Jul 04 2014 15:59:35
%S 23,37,53,73,113,137,173,193,197,211,223,229,233,241,271,283,293,311,
%T 313,317,331,337,347,353,359,367,373,379,383,389,397,433,523,541,547,
%U 571,593,613,617,673,677,719,733,743,761,773,797,977,1013,1033,1093
%N Primes that can be written as concatenation of two primes in decimal representation.
%C Primes that can be written as the concatenation of two distinct primes is the same sequence.
%C Number of terms < 10^n: 0, 4, 48, 340, 2563, 19019, 147249, ... - _T. D. Noe_, Oct 04 2010
%H T. D. Noe, <a href="/A105184/b105184.txt">Table of n, a(n) for n=1..10000</a>
%e 193 is in the sequence because it is the concatenation of the primes 19 and 3.
%e 197 is in the sequence because it is the concatenation of the primes 19 and 7.
%e 199 is not in the sequence because there is no way to break it into two substrings such that both are prime: neither 1 nor 99 is prime, and 19 is prime but 9 is not.
%t searchMax = 10^4; Union[Reap[Do[p = Prime[i]; q = Prime[j]; n = FromDigits[Join[IntegerDigits[p], IntegerDigits[q]]]; If[PrimeQ[n], Sow[n]], {i, PrimePi[searchMax/10]}, {j, 2, PrimePi[searchMax/10^Ceiling[Log[10, Prime[i]]]]}]][[2, 1]]] (* _T. D. Noe_, Oct 04 2010 *)
%Y Subsequence of A019549.
%Y Cf. A121608, A121609, A121610, A019549, A083427.
%K nonn,base
%O 1,1
%A _Lekraj Beedassy_, Apr 11 2005
%E Corrected and extended by _Ray Chandler_, Apr 16 2005
%E Edited by _N. J. A. Sloane_, May 03 2007
%E Edited by _N. J. A. Sloane_, to remove erroneous b-file, comments and Mma program, Oct 04 2010
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