A163431 Primes p such that floor(p^3/8) is also prime.

3, 19, 83, 179, 191, 239, 373, 431, 643, 719, 739, 883, 1123, 1151, 1171, 1237, 1283, 1429, 1459, 1669, 1811, 2053, 2083, 2293, 2351, 2437, 2579, 2677, 2687, 2819, 2851, 2879, 3167, 3253, 3491, 3539, 3877, 4051, 4099, 4483, 4549, 4643, 4799, 5087, 5171

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Jul 27 2009

Keywords

• nonn
• easy

Examples

			a(1)=3 generates 3^3/8=3.375 where 3 is prime.
a(2)=19 generates 19^3/8=857.375 where 857 is prime.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Programs

Mathematica

f[n_]:=IntegerPart[(p/2)^3]; lst={};Do[p=Prime[n];If[PrimeQ[f[p]],AppendTo[lst, p]],{n,7!}];lst

Formula

A163430(n) = floor( a(n)^3/8 ).

Extensions

Mathematica specific notation removed, comments moved to examples - R. J. Mathar, Sep 17 2009