Search: id:A064271
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%I A064271
%S A064271 18,20,36,100,104,196,324,392,464,576,650,784,800,900,968,1352,1936,
%T A064271 1952,2450,2500,3136,4356,4624,5184,6050,6400,9216,10000,10404,10816,
%U A064271 12800,13456,14400,15376,15488,16928,18496,20000,20736,23104,26912
%N A064271 Numbers n such that sigma(n)-2n is prime.
%H A064271 Harry J. Smith, <a href="b064271.txt">Table of n, a(n) for n=1,...,1000</
               a>
%e A064271 n=100: sigma(100)-2*100 = 17.
%o A064271 (PARI) j=[]; for(n=1,50000,x=sigma(n)-2*n; if(x>0 && isprime(x),j=concat(j,
               n))); j
%o A064271 (PARI) { n=0; for (m=1, 10^9, if (isprime(sigma(m) - 2*m), write("b064271.txt", 
               n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), 
               Sep 11 2009]
%Y A064271 Sequence in context: A054279 A164711 A036170 this_sequence A113541 A113542 
               A075865
%Y A064271 Adjacent sequences: A064268 A064269 A064270 this_sequence A064272 A064273 
               A064274
%K A064271 easy,nonn
%O A064271 1,1
%A A064271 Jason Earls (zevi_35711(AT)yahoo.com), Sep 23 2001

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