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A101471 Numbers k such that the number k11 is prime.

%I A101471 #30 Nov 03 2024 02:14:39
%S A101471 0,2,3,8,9,15,18,20,21,23,24,27,30,35,39,41,42,50,57,60,62,63,69,72,
%T A101471 74,80,81,83,90,93,95,98,101,102,107,113,114,120,122,125,126,129,134,
%U A101471 137,140,144,155,161,164,168,170,179,182,183,189,192,200,204,206,210,212
%N A101471 Numbers k such that the number k11 is prime.
%C A101471 k such that 100*k+11 is prime. - _Robert Israel_, Jul 30 2015
%H A101471 Robert Israel, <a href="/A101471/b101471.txt">Table of n, a(n) for n = 1..10000</a>
%H A101471 Chris Caldwell, <a href="https://t5k.org/lists/small/1000.txt">The first 1,000 primes</a>.
%e A101471 If k=2,  then k11 =  211 (prime);
%e A101471 If k=50, then k11 = 5011 (prime);
%e A101471 If k=98, then k11 = 9811 (prime).
%p A101471 select(t -> isprime(100*t+11), [$0..1000]); # _Robert Israel_, Jul 30 2015
%t A101471 Select[ Range[0, 215], PrimeQ[ FromDigits[ Flatten[ IntegerDigits /@ { #, 1, 1}]]] &] (* _Robert G. Wilson v_, Feb 21 2005 *)
%t A101471 Select[Range[0,250],PrimeQ[100#+11]&] (* _Harvey P. Dale_, Oct 11 2018 *)
%o A101471 (Magma) [n: n in [0..250] | IsPrime(Seqint(Intseq(11) cat Intseq(n)))]; // _Vincenzo Librandi_, Jul 31 2015
%o A101471 (Magma) [n: n in [0..240] |IsPrime(100*n+11)]; // _Vincenzo Librandi_, Jul 31 2015
%o A101471 (PARI) is(n)=isprime(100*n+11) \\ _Charles R Greathouse IV_, Feb 20 2017
%Y A101471 Cf. A024912 (10n+1 is prime), A167442 (the actual primes 100n+11).
%K A101471 nonn,base
%O A101471 1,2
%A A101471 _Parthasarathy Nambi_, Jan 30 2005, Feb 18 2005
%E A101471 Corrected and extended by _Robert G. Wilson v_, Feb 21 2005