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%I #17 Feb 15 2017 09:38:37
%S 2,3,3,3,3,3389,63559
%N Smallest value of x + y such that x^(2^k) + y^(2^k) is prime for every k = 0..n, where x > y are nonnegative integers.
%e a(0) = 2 because 2^(2^0) + 0^(2^0) = 2.
%e a(1) = 3 because 2^(2^0) + 1^(2^0) = 3 and 2^(2^1) + 1^(2^1) = 5 are prime.
%e a(2) = 3 because 2^(2^0) + 1^(2^0) = 3, 2^(2^1) + 1^(2^1) = 5, and 2^(2^2) + 1^(2^2) = 17 are prime.
%e a(n) x y
%e ----- ----- -----
%e 2 2 0
%e 3 2 1
%e 3 2 1
%e 3 2 1
%e 3 2 1
%e 3389 2669 720
%e 63559 34559 29000
%Y Cf. A111635.
%K nonn,more
%O 0,1
%A _Altug Alkan_, Feb 12 2017
%E a(6) from _Max Alekseyev_, Feb 14 2017
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