Search: id:A070179
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%I A070179
%S A070179 17,41,97,137,193,241,313,401,409,433,449,457,521,569,641,673,761,769,
%T A070179 809,857,929,953,977,1009,1129,1297,1321,1361,1409,1489,1657,1697,1873,
%U A070179 1993,2017,2081,2137,2153,2161,2297,2377,2417,2521,2609,2617,2633,2713
%N A070179 Primes p such that x^2 = 2 has a solution mod p, but x^(2^2) = 2 has 
               no solution mod p.
%F A070179 Primes of the form 8*k + 1 but not x^2 + 64*y^2. - Michael Somos Mar 
               22 2008
%o A070179 (PARI) forprime(p=2,2720,x=0; while(x<p&&x^2%p!=2%p,x++); if(x<p,y=0; 
               while(y<p&&y^(2^2)%p!=2%p,y++); if(y==p,print1(p,","))))
%o A070179 (PARI) {a(n) = local(m, c, x); if( n<1, 0, c = 0; m = 1; while( c<n, 
               m++; if( isprime(m) & m%8 == 1, x = 0; for(y=1, sqrtint( m \ 64 ), 
               if( issquare( m - 64 * y^2, &x), break)); if( !x, c++ ))); m)} /* 
               Michael Somos Mar 22 2008 */
%Y A070179 Cf. A038873, A040098, A040100, A059667, A070180 - A070188, A014754.
%Y A070179 Sequence in context: A107181 A158014 A139879 this_sequence A155072 A145991 
               A089637
%Y A070179 Adjacent sequences: A070176 A070177 A070178 this_sequence A070180 A070181 
               A070182
%K A070179 nonn
%O A070179 1,1
%A A070179 Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Apr 29 2002

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