A105133 Numbers n such that 8n + 5 is prime.

0, 1, 3, 4, 6, 7, 12, 13, 18, 19, 21, 22, 24, 28, 33, 34, 36, 39, 43, 46, 48, 49, 52, 57, 63, 67, 69, 76, 81, 82, 84, 87, 88, 91, 94, 96, 99, 102, 103, 106, 109, 117, 124, 126, 127, 132, 133, 136, 138, 139, 147, 151, 153, 154, 159, 162, 171, 172, 178, 181, 186, 193, 199, 201, 202

Offset: 1

Author

N. J. A. Sloane, based on correspondence from Marco Matosic, Apr 11 2005

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A095278, A105134-A105140, A002145, A007521, A105126-A105132.

Programs

Magma

[n: n in [0..500] | IsPrime(8*n+5)];  // Vincenzo Librandi, Jan 07 2013

Maple

M:=500; f:=proc(n) local t1,t2; t1:=[]; for k from 0 to M do t2:=2^n*k+2^(n-1)+1; if isprime(t2) then t1:=[op(t1),k]; fi; od; t1; end; f(3);

Mathematica

Select[Range[0, 300], PrimeQ[8 # + 5]&] (* Vincenzo Librandi, Jan 07 2013 *)

PARI

is(n)=isprime(8*n+5) \\ Charles R Greathouse IV, Feb 17 2017

Formula

a(n) = (A007521(n)-5)/8. - Zak Seidov, Sep 08 2015