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 A255340 #39 Jan 11 2020 15:57:46 %S A255340 4,7,12,64, %T A255340 13407807929942597099574024998205846127479365820592393377723561443721764030073546976801874298166903427690031858186486050853753882811946569946433649006084096 %N A255340 a(n) = H_n(4,3) where H_n is the n-th hyperoperator. %C A255340 See A054871 for definitions and key links. %e A255340 a(0) = H_0(4,3) = 3+1 = 4; %e A255340 a(1) = H_1(4,3) = 4+3 = 7; %e A255340 a(2) = H_2(4,3) = 4*3 = 12; %e A255340 a(3) = H_3(4,3) = 4^3 = 64; %e A255340 a(4) = H_4(4,3) = 4^^3 = 4^4^4 = 4^256 = ... ; %e A255340 a(5) = H_5(4,3) = 4^^^3 = 4^^4^^4 = 4^^(4^4^4^4) = 4^^(4^4^256) = ... . %Y A255340 Cf. A054871. %K A255340 nonn %O A255340 0,1 %A A255340 _Natan Arie Consigli_, Apr 18 2015 %E A255340 First term corrected and hyperoperator notation implemented by _Danny Rorabaugh_, Oct 20 2015