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A101472 Numbers k such that the number k33 is prime.

%I A101472 #25 Aug 03 2025 13:52:40
%S A101472 2,4,7,10,14,17,19,23,26,28,34,35,37,38,41,47,49,52,53,61,67,68,73,74,
%T A101472 79,82,89,91,94,95,97,98,101,103,104,107,116,118,119,124,130,136,139,
%U A101472 140,145,146,152,157,160,163,164,166,170,173,181,182,184,193,194,202
%N A101472 Numbers k such that the number k33 is prime.
%H A101472 Daniel Starodubtsev, <a href="/A101472/b101472.txt">Table of n, a(n) for n = 1..10000</a>
%H A101472 Chris Caldwell <a href="https://t5k.org/lists/small/1000.txt">The first 1,000 primes</a>.
%e A101472 If k=2,  then k33 =  233 (prime);
%e A101472 If k=34, then k33 = 3433 (prime);
%e A101472 If k=74, then k33 = 7433 (prime).
%t A101472 fQ[n_] := PrimeQ[FromDigits[ Join[ IntegerDigits[n], {3, 3}]]]; Select[ Range[203], fQ[ # ] &] (* _Robert G. Wilson v_, Feb 04 2005 *)
%t A101472 Select[Range[250], PrimeQ[FromDigits[Flatten[{IntegerDigits[#], IntegerDigits[33]}]]] &] (* _Vincenzo Librandi_, Jul 31 2015 *)
%t A101472 Select[Range[210],PrimeQ[100#+33]&] (* _Harvey P. Dale_, Jul 04 2017 *)
%o A101472 (Magma) [n: n in [0..250] | IsPrime(Seqint(Intseq(33) cat Intseq(n)))]; // _Vincenzo Librandi_, Jul 31 2015
%o A101472 (PARI) is(n)=isprime(100*n+33) \\ _Charles R Greathouse IV_, May 22 2017
%Y A101472 Cf. A090263, A109369.
%K A101472 nonn,base
%O A101472 1,1
%A A101472 _Parthasarathy Nambi_, Jan 30 2005
%E A101472 More terms from _Robert G. Wilson v_, Feb 04 2005