login
A101471
Numbers k such that the number k11 is prime.
4
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
1,2
COMMENTS
k such that 100*k+11 is prime. - Robert Israel, Jul 30 2015
LINKS
EXAMPLE
If k=2, then k11 = 211 (prime);
If k=50, then k11 = 5011 (prime);
If k=98, then k11 = 9811 (prime).
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 *)
PROG
(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
(PARI) is(n)=isprime(100*n+11) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
Cf. A024912 (10n+1 is prime), A167442 (the actual primes 100n+11).
Sequence in context: A029787 A246396 A054462 * A137471 A051209 A332481
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Jan 30 2005, Feb 18 2005
EXTENSIONS
Corrected and extended by Robert G. Wilson v, Feb 21 2005
STATUS
approved