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%I #12 Sep 08 2022 08:45:35
%S 29,89,109,149,229,269,349,389,409,449,509,569,709,769,809,829,929,
%T 1009,1049,1069,1109,1129,1229,1249,1289,1409,1429,1489,1549,1609,
%U 1669,1709,1789,1889,1949,2029,2069,2089,2129,2269,2309,2389,2549,2609,2689,2729
%N Primes congruent to 9 mod 20.
%H Vincenzo Librandi, <a href="/A141883/b141883.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[9,5000,20],PrimeQ[#]&] (* _Vladimir Joseph Stephan Orlovsky_, Mar 31 2011*)
%o (Magma) [p: p in PrimesUpTo(3000) | p mod 20 eq 9 ]; // _Vincenzo Librandi_, Aug 16 2012
%o (PARI) is(n)=isprime(n) && n%20==9 \\ _Charles R Greathouse IV_, Jul 01 2016
%Y Cf. A000040, A105854, A141881, A141882.
%K nonn,easy
%O 1,1
%A _N. J. A. Sloane_, Jul 11 2008