Search: id:A065727
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%I A065727
%S A065727 2,3,5,7,37,43,61,109,127,199,271,277,379,457,487,523,541,613,619,673,
%T A065727 727,757,883,907,919,991,997,1033,1117,1249,1447,1483,1531,1549,1567,
%U A065727 1627,1693,1699,1747,1753,1987,2053,2161,2221,2287,2341,2347,2437,2473
%N A065727 Primes p such that the decimal expansion of its base 9 conversion is 
               also prime.
%C A065727 In general rebase notation (Marc LeBrun): p(n) = (9) [p] (10).
%H A065727 Harry J. Smith, <a href="b065727.txt">Table of n, a(n) for n=1,...,1000</
               a>
%e A065727 E.g. 997{10} = 1327{9} is prime but also 1327{10}.
%t A065727 Select[ Range[2500], PrimeQ[ # ] && PrimeQ[ FromDigits[ IntegerDigits[ 
               #, 9]]] & ]
%o A065727 (PARI) baseE(x, b)= { local(d, e=0, f=1); while (x>0, d=x-b*(x\b); x\=b; 
               e+=d*f; f*=10); return(e) } { n=0; for (m=1, 10^9, p=prime(m); b=baseE(p, 
               9); if (isprime(b), write("b065727.txt", n++, " ", p); if (n==1000, 
               return)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Oct 
               28 2009]
%Y A065727 Cf. A065720 up to A065726, A065361.
%Y A065727 Sequence in context: A067907 A048415 A029974 this_sequence A090713 A090912 
               A048416
%Y A065727 Adjacent sequences: A065724 A065725 A065726 this_sequence A065728 A065729 
               A065730
%K A065727 nonn,base
%O A065727 1,1
%A A065727 Patrick De Geest (pdg(AT)worldofnumbers.com), Nov 15 2001.

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