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Pseudoprimes n to base 2 such that n-2, n+2, n-4 and n+4 are primes.
2

%I #14 Aug 06 2017 18:43:42

%S 280743771536011785,666787209284980785,1386744766793550165,

%T 6558237049521329745,11646802313400102465

%N Pseudoprimes n to base 2 such that n-2, n+2, n-4 and n+4 are primes.

%C All numbers in this sequence end in 5 because n-4 , n-2 is a twin prime pair and so also is n+2 and n+4.

%C For all n, a(n) - 4 is in A230668(n). Somewhat surprisingly, all terms of A230668 known so far are of that form. - _M. F. Hasler_, Dec 08 2016

%e 280743771536011785 is a pseudoprime (base 2) and 280743771536011781, 280743771536011783, 280743771536011787 and 280743771536011789 are primes.

%Y Cf. A001567, A057942, A230488, A230489.

%K nonn,more,hard

%O 1,1

%A _Shyam Sunder Gupta_, Oct 27 2013