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Primes p such that p + floor(sqrt(p)) OR p + ceiling(sqrt(p)) is also prime.
1

%I #7 Oct 07 2016 19:19:21

%S 2,3,5,13,19,31,37,41,47,53,59,71,97,103,127,137,139,151,167,179,197,

%T 241,277,293,313,331,349,389,401,419,457,487,499,547,563,569,577,593,

%U 607,617,619,647,683,701,733,769,811,829,853,857,877,881,907,911,937

%N Primes p such that p + floor(sqrt(p)) OR p + ceiling(sqrt(p)) is also prime.

%F A145907 UNION A086085. - _R. J. Mathar_, Oct 31 2008

%e p = 3; 3 + ceiling(sqrt(3)) = 5, which is prime. p = 5; 5 + floor(sqrt(5)) = 7, which is prime.

%p for n from 1 to 820 do p := ithprime(n) ; f := p+floor(sqrt(p)) ; c := p+ceil(sqrt(p)) ; if isprime(f) or isprime(c) then printf("%d,",p) ; fi; od: # _R. J. Mathar_, Oct 31 2008

%Y Cf. A145907, A086085.

%K nonn

%O 1,1

%A _Kyle D. Balliet_, Oct 24 2008, Nov 06 2008

%E 2 terms inserted and sequence extended by _R. J. Mathar_, Oct 31 2008