A086086 Primes p such that p - floor(sqrt(p)) is prime.

3, 5, 7, 17, 23, 37, 43, 47, 67, 79, 107, 113, 149, 151, 163, 211, 257, 331, 349, 409, 421, 439, 509, 521, 587, 593, 601, 617, 709, 727, 797, 839, 907, 911, 937, 941, 1051, 1063, 1163, 1187, 1319, 1327, 1447, 1471, 1489, 1607, 1619, 1637, 1667, 1783, 1789, 1801

Offset: 1

Author

Chuck Seggelin, Jul 08 2003

Keywords

• nonn

Examples

			a(5)=23 because 19 is prime and 23 - floor(sqrt(23)) = 23 - floor(4.795831523) = 23 - 4 = 19, which is prime.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Programs

Mathematica

f[n_]:=n-Floor[Sqrt[n]];lst={};Do[p=Prime[n];If[PrimeQ[f[p]],AppendTo[lst,p]],{n,7!}];lst (* Vladimir Joseph Stephan Orlovsky, Feb 25 2010 *)
Select[Prime[Range[300]],PrimeQ[#-Floor[Sqrt[#]]]&] (* Harvey P. Dale, Sep 26 2017 *)

Extensions

More terms from Vladimir Joseph Stephan Orlovsky, Feb 25 2010