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%I #20 Apr 17 2024 07:50:43
%S 7,9,21,261,65541,4294967301,18446744073709551621,
%T 340282366920938463463374607431768211461,
%U 115792089237316195423570985008687907853269984665640564039457584007913129639941
%N a(n) = 2^(2^n) + 5.
%D D. M. Burton, Elementary Number Theory, Allyn and Bacon Inc., Boston, MA, 1976, p. 238.
%H Harry J. Smith, <a href="/A063486/b063486.txt">Table of n, a(n) for n=0..11</a>
%H Tigran Hakobyan, <a href="http://arxiv.org/abs/1601.04946">On the unboundedness of common divisors of distinct terms of the sequence a(n)=2^2^n+d for d>1</a>, arXiv:1601.04946 [math.NT], 2016.
%t 2^2^Range[0, 10] + 5 (* _Paolo Xausa_, Apr 17 2024 *)
%o (PARI) for(n=0,8,print1(2^(2^n)+5), ", ")
%o (PARI) { for (n=0, 11, write("b063486.txt", n, " ", 2^(2^n) + 5) ) } \\ _Harry J. Smith_, Aug 23 2009
%Y Cf. A000215, A001146, A130729, A130730.
%K easy,nonn
%O 0,1
%A _Jason Earls_, Jul 28 2001
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