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%I #8 May 22 2013 03:34:02
%S 1,3,4,6,7
%N Numbers n such that there are no primes in the open interval from (n^2-1)*sqrt(n^2+1) to (n^2+1)*sqrt(n^2-1).
%C Sequence is probably complete. a(6), if it exists, is greater than 4 * 10^18. - _Charles R Greathouse IV_, May 14 2013
%o (PARI) is(n)=n==1 || nextprime(sqrtint((n^2+1)*(n^2-1)^2-1)+1) > sqrtint((n^2-1)*(n^2+1)^2-1) \\ _Charles R Greathouse IV_, May 14 2013
%K nonn
%O 1,2
%A _Gerasimov Sergey_, May 11 2013
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