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%I #12 Mar 26 2024 05:04:45
%S 37,163,15667,142543,607093,671353,1457857,2694157,2979043,4890307,
%T 5772097,6404773,9139453,10669003,11170933,11218747,11905987,13243063,
%U 15130537,18116473,19433863,21960577,23524183,25946083,32380177,45600157,46960747,51905137
%N a(n) and a(n)+4^k are primes at least for k=1,2,3,4,5,6,7.
%H Robert Israel, <a href="/A049497/b049497.txt">Table of n, a(n) for n = 1..200</a>
%F A023200 INTERSECT A269859. - _R. J. Mathar_, Mar 26 2024
%e 37, 37+4=41, 37+16=53, 37+64=101, 37+256=293, 37+1024=1061, 37+4096=4133, 37+16384=16421 are all primes; the smallest such a 8-chain of primes is {37,41,53,101,293,1061,4133,16421}.
%p filter:= n -> andmap(isprime, [n,n+4,n+4^2,n+4^3,n+4^4,n+4^5,n+4^6,n+4^7]):
%p select(filter, [seq(i,i=7..10^7,6)]); #_Robert Israel_, Nov 11 2019
%o (PARI) isok(n) = isprime(n) && isprime(n+4) && isprime(n+16) && isprime(n+64) && isprime(n+256) && isprime(n+1024) && isprime(n+4096) && isprime(n+16384); \\ _Michel Marcus_, Dec 22 2013
%Y Cf. A023200, A049492-A049496, A049498-A049500.
%K nonn
%O 1,1
%A _Labos Elemer_
%E More terms from _Michel Marcus_, Dec 22 2013
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