A153355 Numbers k such that 5k-1 is a prime.

4, 6, 12, 16, 18, 22, 28, 30, 36, 40, 46, 48, 54, 70, 72, 76, 78, 82, 84, 88, 90, 96, 100, 102, 114, 120, 124, 132, 142, 144, 148, 154, 162, 166, 168, 172, 184, 186, 202, 204, 208, 210, 214, 222, 226, 246, 250, 252, 256, 258, 264, 280, 282, 286, 288, 292, 298

Offset: 1

Author

Vincenzo Librandi, Dec 24 2008

Keywords

• nonn
• easy

Comments

One more than the value of A024897 at the same index. - R. J. Mathar, Jan 05 2009

Examples

			5*4 - 1 = 19 is a prime, so 4 is a term;
5*30 - 1 = 149 is a prime, so 30 is a term.
		

Links

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

Programs

Magma

[n: n in [0..300] | IsPrime(5*n - 1)]; // Vincenzo Librandi, Sep 24 2012

Mathematica

Select[Range[400],PrimeQ[5#-1]&] (* Vladimir Joseph Stephan Orlovsky, Feb 25 2011*)

Formula

The set of numbers (1+A030433(k))/5, k=1,2,3,4,.... - R. J. Mathar, Jan 03 2009

Extensions

Extended by R. J. Mathar, Jan 05 2009