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 A230874 #19 Oct 16 2018 11:24:07 %S A230874 1,2,4,4,16,16,16,16,65536,65536,65536,65536,65536,65536,65536,65536 %N A230874 a(1)=1; thereafter a(n) = 2^a(ceiling(n/2)). %C A230874 a(17) through a(32) are 2^65536, %C A230874 a(33) through a(64) are 2^2^65536, etc. %F A230874 For n>1, a(n) = a tower of 2's of height ceiling(log_2(n)). E.g. a(15) = 2^2^2^2. %Y A230874 Cf. A230863, A230875. %K A230874 nonn %O A230874 1,2 %A A230874 _N. J. A. Sloane_, Nov 07 2013