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%I #9 Apr 03 2023 10:36:11
%S 43,47,419,431,443,461,467,479,4127,4139,4157,4211,4229,4241,4271,
%T 4283,4337,4349,4373,4397,4409,4421,4457,4463,4523,4547,4643,4673,
%U 4691,4733,4751,4787,4877,4919,4937,4967,41039,41051,41117,41201,41213,41231,41381,41399
%N Primes obtained from other primes by prefixing a 4.
%H Harvey P. Dale, <a href="/A165444/b165444.txt">Table of n, a(n) for n = 1..1000</a>
%H Chris Caldwell, <a href="https://t5k.org/lists/small/10000.txt">The First 10,000 Primes</a>
%e 4547 is a prime obtained by prefixing a 4 to the prime 547.
%t Select[4*10^IntegerLength[#]+#&/@Prime[Range[300]],PrimeQ] (* _Harvey P. Dale_, Mar 25 2016 *)
%Y Cf. A000040, A165243, A165292
%K base,nonn
%O 1,1
%A _Parthasarathy Nambi_, Sep 19 2009
%E More terms from _Vincenzo Librandi_, Sep 20 2009
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