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%I #17 Sep 08 2022 08:45:17
%S 3,33,37,39,81,99,103,121,139,141,169,189,223,229,247,253,261,271,303,
%T 339,349,357,363,379,439,451,453,457,481,511,537,583,591,609,643,651,
%U 657,667,687,691,721,723,733,741,747,759,763,769,789,799,813,819,831
%N Numbers n such that the string 10000n is the decimal expansion of a prime number.
%C All terms == 1 or 3 (mod 6). - _Robert Israel_, Mar 27 2018
%H Robert Israel, <a href="/A103862/b103862.txt">Table of n, a(n) for n = 1..10000</a>
%e 3 is in the sequence because 100003 is prime.
%e 81 is in the sequence because 1000081 is prime.
%e 247 is in the sequence because 10000247 is prime.
%p select(n -> isprime(n+10^(ilog10(n)+5)), [seq(seq(6*i+j,j=[1,3]),i=0..1000)]); # _Robert Israel_, Mar 27 2018
%t Select[Range[1000],PrimeQ[10000*10^IntegerLength[#]+#]&] (* _Harvey P. Dale_, Jun 30 2020 *)
%o (Magma) [ n: n in [1..900] | IsPrime(Seqint(Intseq(n) cat [0, 0, 0, 0, 1])) ]; // _Klaus Brockhaus_, Feb 02 2011
%Y Cf. A103601, A103602, A103603.
%K base,nonn
%O 1,1
%A _Parthasarathy Nambi_, Mar 30 2005
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