A105106 Numbers k such that the string k101 is prime.

0, 5, 6, 8, 12, 15, 20, 21, 29, 42, 44, 50, 53, 54, 56, 60, 65, 72, 74, 77, 78, 81, 83, 89, 95, 98, 102, 107, 116, 117, 119, 125, 131, 135, 138, 141, 149, 170, 174, 177, 182, 194, 197, 201, 204, 210, 221, 224, 230, 240, 242, 243, 252, 258, 261, 263, 264, 282, 285, 291

Offset: 1

Author

Parthasarathy Nambi, Apr 07 2005

Keywords

• base
• nonn

Comments

Also numbers k such that 1000*k + 101 is prime. - Stefan Steinerberger, Feb 21 2006

Examples

			If k=0,  then k101 =  0101 (prime).
If k=42, then k101 = 42101 (prime).
		

Links

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

Programs

Maple

q:= n-> isprime(parse(cat(n, 101))):
select(q, [$0..300])[];  # Alois P. Heinz, Jan 23 2020

Mathematica

For[n = 0, n < 300, n++, If[PrimeQ[1000*n + 101], Print[n]]] (* Stefan Steinerberger, Feb 21 2006 *)

PARI

is(n)=isprime(1000*n+101) \\ Charles R Greathouse IV, May 22 2017

Extensions

More terms from Stefan Steinerberger, Feb 21 2006

Missing a(11)=44 inserted by Daniel Starodubtsev, Jan 23 2020