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 A081784 #19 Apr 24 2025 01:31:31
%S A081784 1,10,122,33429,1447509608,3251816299888840778,
%T A081784 10657606087425320549792856871886476385,
%U A081784 1233698091085791193532165615536619532897409600456434390187369062304735077655
%N A081784 Continued cotangent for zeta(3).
%F A081784 zeta(3) = cot(Sum_{n>=0} (-1)^n*acot(a(n))).
%F A081784 Let b(0) = zeta(3), b(n) = (b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))) then a(n) = floor(b(n)).
%o A081784 (PARI) \p900
%o A081784 bn=vector(100);
%o A081784 bn[1]=zeta(3);
%o A081784 b(n)=if(n<0,0,bn[n]);
%o A081784 for(n=2,10,bn[n]=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))));
%o A081784 a(n)=floor(b(n+1));
%Y A081784 Cf. A001620, A002666, A002667.
%K A081784 nonn
%O A081784 0,2
%A A081784 _Benoit Cloitre_, Apr 10 2003