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 A264610 #4 Nov 25 2015 02:03:52
%S A264610 1,-1,-2,-6,-54,-4470,-30229110,-1388162822415990,
%T A264610 -2926650008246700930753649260150,
%U A264610 -13001299396349738096788020339357180951040927696209747704510070
%N A264610 a(0)=1; thereafter a(n) = -Sum_{i=1..n} a(n-i)^(2^i).
%p A264610 f:=proc(n) option remember;
%p A264610 if n=0 then 1 else -add(f(n-i)^(2^i),i=1..n); fi; end;
%p A264610 [seq(f(n),n=0..4)];
%Y A264610 Equals A260685(2^n).
%K A264610 sign
%O A264610 0,3
%A A264610 _N. J. A. Sloane_, Nov 25 2015