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%I #9 Aug 26 2014 08:50:08
%S 7,11,23,37,41,67,71,97,113,137,163,191,197,263,307,317,401,421,491,
%T 617,653,683,727,823,881,883,907,947,953,967,1031,1087,1103,1217,1231,
%U 1297,1451,1493,1523,1567,1693,1747,1933,1973,2053,2141,2207,2221,2281,2293
%N Primes p such that 4p+9 and 9p+4 are both prime.
%C All numbers in this sequence are either 1, 3, or 7 mod 10.
%H Harvey P. Dale, <a href="/A239733/b239733.txt">Table of n, a(n) for n = 1..1000</a>
%e 7 is prime, 4*7+9 = 37 is prime, and 9*7+4 = 67 is prime. Thus, 7 is a member of this sequence.
%t Select[Prime[Range[400]],AllTrue[{4#+9,9#+4},PrimeQ]&] (* The program uses the AllTrue function from Mathematica version 10 *) (* _Harvey P. Dale_, Aug 26 2014 *)
%o (Python)
%o import sympy
%o from sympy import isprime
%o {print(n) for n in range(5000) if isprime(4*n+9) and isprime(9*n+4) and isprime(n)}
%o (PARI) s=[]; forprime(p=2, 3000, if(isprime(4*p+9) && isprime(9*p+4), s=concat(s, p))); s \\ _Colin Barker_, Mar 26 2014
%K nonn,easy
%O 1,1
%A _Derek Orr_, Mar 25 2014
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