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 A253855 #25 Nov 12 2024 22:16:51
%S A253855 3,6,8,16,256
%N A253855 a(n) = H_n(4,2) where H_n is the n-th hyperoperator.
%C A253855 See A054871 for definitions and key links.
%C A253855 This sequence is also a(0)=0, a(1)=1, a(n)=H_{n-1}(4,4) for n>1.
%e A253855 a(0) = H_0(4,2) = 2+1 = 3
%e A253855 a(1) = H_1(4,2) = 4+2 = 6.
%e A253855 a(2) = H_2(4,2) = 4*2 = 8.
%e A253855 a(3) = H_3(4,2) = 4^2 = 16.
%e A253855 a(4) = H_4(4,2) = 4^^2 = 4^4 = 256.
%e A253855 a(5) = H_5(4,2) = 4^^^2 = 4^^4 = 4^4^4^4 = 4^4^256 = ...
%Y A253855 Cf. A054871, A067652.
%K A253855 nonn,less
%O A253855 0,1
%A A253855 _Natan Arie Consigli_, May 02 2015
%E A253855 First term corrected and hyperoperator notation implemented by _Danny Rorabaugh_, Oct 20 2015