A111094 Numbers k such that 18*k + 1 is prime.

1, 2, 4, 6, 7, 9, 10, 11, 15, 17, 21, 22, 24, 27, 29, 30, 32, 34, 35, 41, 42, 45, 46, 49, 51, 52, 55, 56, 59, 62, 64, 65, 71, 72, 79, 81, 85, 86, 87, 90, 92, 94, 97, 99, 100, 104, 111, 112, 114, 116, 119, 120, 121, 125, 126, 127, 130, 132, 137, 139, 140, 141, 142, 144

Offset: 1

Author

Parthasarathy Nambi, Oct 20 2005

Keywords

• nonn
• easy

Comments

a(n) = A024906(n)/2. - Zak Seidov, Feb 02 2010

Examples

			If k=99 then 18*k + 1 = 1783 (prime).
		

Links

• Daniel Starodubtsev, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A024906.

Programs

Magma

[ n: n in [0..1500] | IsPrime(18*n + 1) ]; // Vincenzo Librandi, Jan 31 2011

Mathematica

Select[Range[200],PrimeQ[18#+1]&]  (* Harvey P. Dale, Mar 14 2011 *)

PARI

is(n)=isprime(18*n+1) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

More terms from Zak Seidov, Feb 02 2010