This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A063486 #26 Jul 20 2025 13:07:56
%S A063486 7,9,21,261,65541,4294967301,18446744073709551621,
%T A063486 340282366920938463463374607431768211461,
%U A063486 115792089237316195423570985008687907853269984665640564039457584007913129639941
%N A063486 a(n) = 2^(2^n) + 5.
%D A063486 D. M. Burton, Elementary Number Theory, Allyn and Bacon Inc., Boston, MA, 1976, p. 238.
%D A063486 James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, Example 5.1 on page 153.
%H A063486 Harry J. Smith, <a href="/A063486/b063486.txt">Table of n, a(n) for n=0..11</a>
%H A063486 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 A063486 2^2^Range[0, 10] + 5 (* _Paolo Xausa_, Apr 17 2024 *)
%o A063486 (PARI) for(n=0,8,print1(2^(2^n)+5, ", "))
%o A063486 (PARI) { for (n=0, 11, write("b063486.txt", n, " ", 2^(2^n) + 5) ) } \\ _Harry J. Smith_, Aug 23 2009
%o A063486 (SageMath) [2**2**n + 5 for n in (0..8)] # _Stefano Spezia_, Jul 20 2025
%Y A063486 Cf. A000215, A001146, A130729, A130730.
%K A063486 easy,nonn
%O A063486 0,1
%A A063486 _Jason Earls_, Jul 28 2001