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%I #21 Jun 30 2017 11:38:01
%S 1387,2047,3277,7957,13747,23377,31417,60787,65077,88357,164737,
%T 188057,233017,275887,390937,486737,489997,514447,580337,604117,
%U 672487,680627,769567,769757,916327,1092547,1132657,1145257,1252697,1293337,1433407,1493857,1530787
%N Semiprime 2-pseudoprimes of the form 10k + 7.
%C A very interesting observation due to _Peter Bala_: about half of the terms from the sequence have the form p*(4*p - 3), where p is prime. For this form of Fermat pseudoprimes see the sequences A213812 and A215343.
%H Charles R Greathouse IV, <a href="/A216667/b216667.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PouletNumber.html">Poulet Number</a>
%o (PARI) list(lim)=my(v=List(),t); forprime(p=3,sqrtint(lim\=1), forprime(q=p+2,lim\p, t=p*q; if(t%10==7 && Mod(2,t)^t==2, listput(v,t)))); Set(v) \\ _Charles R Greathouse IV_, Jun 30 2017
%Y Subsequence of A214305.
%Y Cf. A001567.
%K nonn
%O 1,1
%A _Marius Coman_, Sep 13 2012