A153355 - OEIS

%I #17 Jan 23 2022 20:03:29

%S 4,6,12,16,18,22,28,30,36,40,46,48,54,70,72,76,78,82,84,88,90,96,100,

%T 102,114,120,124,132,142,144,148,154,162,166,168,172,184,186,202,204,

%U 208,210,214,222,226,246,250,252,256,258,264,280,282,286,288,292,298

%N Numbers k such that 5k-1 is a prime.

%C One more than the value of A024897 at the same index. - _R. J. Mathar_, Jan 05 2009

%H Vincenzo Librandi, <a href="/A153355/b153355.txt">Table of n, a(n) for n = 1..1000</a>

%F The set of numbers (1+A030433(k))/5, k=1,2,3,4,.... - _R. J. Mathar_, Jan 03 2009

%e 5*4 - 1 = 19 is a prime, so 4 is a term;

%e 5*30 - 1 = 149 is a prime, so 30 is a term.

%t Select[Range[400],PrimeQ[5#-1]&] (* _Vladimir Joseph Stephan Orlovsky_, Feb 25 2011*)

%o (Magma) [n: n in [0..300] | IsPrime(5*n - 1)]; // _Vincenzo Librandi_, Sep 24 2012

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Dec 24 2008

%E Extended by _R. J. Mathar_, Jan 05 2009