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A144620 Numbers k such that k and 19*k + 8 are both prime.

%I A144620 #11 Sep 08 2022 08:45:38
%S A144620 5,17,41,59,89,167,191,239,269,281,359,449,479,491,509,521,587,617,
%T A144620 647,701,719,821,881,911,929,971,1031,1181,1217,1259,1289,1307,1361,
%U A144620 1367,1559,1601,1697,1709,1721,1787,1877,1889,1907,1931,1949,1997,2039,2129
%N A144620 Numbers k such that k and 19*k + 8 are both prime.
%H A144620 Vincenzo Librandi, <a href="/A144620/b144620.txt">Table of n, a(n) for n = 1..1000</a>
%e A144620 For n=5, 19*5 + 8 = 103;
%e A144620 for n=269, 19*269 + 8 = 5119.
%p A144620 a := proc (n) if isprime(n) = true and isprime(19*n+8) = true then n else end if end proc: seq(a(n), n = 1 .. 2300); # _Emeric Deutsch_, Jan 27 2009
%t A144620 Select[Prime[Range[400]], PrimeQ[#] &&PrimeQ[19#+8] &] (* _Vincenzo Librandi_, Aug 30 2012 *)
%o A144620 (Magma) [p: p in PrimesUpTo(2500)|IsPrime(19*p+8)] // _Vincenzo Librandi_, Aug 30 2012
%Y A144620 Cf. A141873, A144619.
%K A144620 nonn,easy
%O A144620 1,1
%A A144620 _Vincenzo Librandi_, Jan 15 2009
%E A144620 Extended by _Emeric Deutsch_, Jan 27 2009