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 A247269 Primes p such that p + m^2 is prime for all m in {2,4,6,8,10,12,14,16,18}. 4

%I

%S 163,409333,1483087,1867783,222640867,258001837,371305267,748576753,

%T 828497443,1235054137,2059599067,5767711867,5929920613,8965599883,

%U 9055004953,9170160343,9655686727,9670115977,9671300983,10646399437,12253792783,12627473917,19635778453

%N Primes p such that p + m^2 is prime for all m in {2,4,6,8,10,12,14,16,18}.

%C All terms are == 1 mod 6, and == {7, 13} mod 30.

%C Subsequence of A246842.

%H Zak Seidov, <a href="/A247269/b247269.txt">Table of n, a(n) for n = 1..1592</a>

%o (PARI)

%o forprime(p=1,10^12,c=0;for(i=1,9,if(ispseudoprime(p+(2*i)^2),c++);if(!ispseudoprime(p+(2*i)^2),break));if(c==9,print1(p,", "))) \\ _Derek Orr_, Sep 11 2014

%o (PARI) is(n)=my(t=n%5); if(t!=2 && t!=3, return(0)); forstep(i=4,18,2, if(!isprime(n+i^2),return(0))); isprime(n) && isprime(n+4)

%o p=2; forprime(q=3,1e12, if(q-p==4 && is(p), print1(p", ")); p=q) \\ _Charles R Greathouse IV_, Sep 11 2014

%Y Cf. A049492, A092120, A246842.

%K nonn

%O 1,1

%A _Zak Seidov_, Sep 11 2014

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Last modified June 1 18:43 EDT 2020. Contains 334762 sequences. (Running on oeis4.)