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%I #6 Dec 22 2018 12:53:25
%S 5,5,5,59,7,31,5,5,5,11,31,7,23,5,11,5,7,23,79,29,5,5,73,29,7,41,107,
%T 43,19,59,11,37,13,79,13,11,17,43,359,23,31,5,53,19,47,181,137,23,59,7
%N Smallest prime a(n) such that a(n)+6n, a(n)+12n and a(n)+18n are also primes.
%C a(1) starts sequence A023271.
%e a(5) = 7: 7+6(5) = 7+30 = 37 which is prime. 7+12(5) = 7+60 = 67 which is prime. 7+18(5) = 7+90 = 97 which is prime.
%t Module[{nn=100,prs},prs=Prime[Range[nn]];Table[SelectFirst[prs, AllTrue[ #+6*Range[3]*n,PrimeQ]&],{n,nn/2}]] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Dec 22 2018 *)
%K nonn
%O 1,1
%A _Ray G. Opao_, Apr 06 2004
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