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Smallest k such that 3^(3^n) - k is prime.
3

%I #20 Aug 24 2024 06:59:42

%S 1,4,2,26,10,466,506,128,13342,5974,8410,6470

%N Smallest k such that 3^(3^n) - k is prime.

%C This is to 3 as A058220 is to 2.

%F a(n) = A064722(A055777(n)). - _Michel Marcus_, Jan 28 2015

%e a(4) = 10 because 3^(3^4) - 10 = 443426488243037769948249630619149892793 is prime.

%o (PARI) a(n) = x = 3^(3^n); x - precprime(x); \\ _Michel Marcus_, Jan 28 2015

%Y Cf. A055777 (3^(3^n)), A058220.

%K more,nonn

%O 0,2

%A _Jonathan Vos Post_, May 26 2008

%E a(5)-a(8) from _Cino Hilliard_, Jun 02 2008

%E a(9)-a(10) from _Donovan Johnson_, Sep 13 2008

%E a(0) prepended and a(11) from _Michael S. Branicky_, Aug 23 2024