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

%I #34 Aug 25 2019 17:55:36

%S 645,656601,6212361,18958567881,287468425245,626160901281,

%T 1395494019921,1925525109201,1960708164801,1962378065901,

%U 1977370759365,2788325761551,3032013857181,6877227801081,22298617759881,30242009317521,39454593651201,42401101442001

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

%C All numbers in this sequence end in either 5 or 1.

%H Shyam Sunder Gupta, <a href="/A228575/b228575.txt">Table of n, a(n) for n = 1..831</a>

%e 645 is a pseudoprime (base 2) and 641, 643 and 647 are primes.

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

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Oct 27 2013