A101471 Numbers k such that the number k11 is prime.

0, 2, 3, 8, 9, 15, 18, 20, 21, 23, 24, 27, 30, 35, 39, 41, 42, 50, 57, 60, 62, 63, 69, 72, 74, 80, 81, 83, 90, 93, 95, 98, 101, 102, 107, 113, 114, 120, 122, 125, 126, 129, 134, 137, 140, 144, 155, 161, 164, 168, 170, 179, 182, 183, 189, 192, 200, 204, 206, 210, 212

Offset: 1

Author

Parthasarathy Nambi, Jan 30 2005, Feb 18 2005

Keywords

• nonn
• base

Comments

k such that 100*k+11 is prime. - Robert Israel, Jul 30 2015

Examples

			If k=2,  then k11 =  211 (prime);
If k=50, then k11 = 5011 (prime);
If k=98, then k11 = 9811 (prime).
		

Links

• Robert Israel, Table of n, a(n) for n = 1..10000
• Chris Caldwell, The first 1,000 primes.

Crossrefs

Cf. A024912 (10n+1 is prime), A167442 (the actual primes 100n+11).

Programs

Magma

[n: n in [0..250] | IsPrime(Seqint(Intseq(11) cat Intseq(n)))]; // Vincenzo Librandi, Jul 31 2015

Magma

[n: n in [0..240] |IsPrime(100*n+11)]; // Vincenzo Librandi, Jul 31 2015

Maple

select(t -> isprime(100*t+11), [$0..1000]); # Robert Israel, Jul 30 2015

Mathematica

Select[ Range[0, 215], PrimeQ[ FromDigits[ Flatten[ IntegerDigits /@ { #, 1, 1}]]] &] (* Robert G. Wilson v, Feb 21 2005 *)
Select[Range[0,250],PrimeQ[100#+11]&] (* Harvey P. Dale, Oct 11 2018 *)

PARI

is(n)=isprime(100*n+11) \\ Charles R Greathouse IV, Feb 20 2017

Extensions

Corrected and extended by Robert G. Wilson v, Feb 21 2005