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 A081794 #13 Apr 24 2025 06:12:50
%S A081794 0,1,8,211,114681,118304381067,14093169772574392414247,
%T A081794 233069007722838136376547872705625127588988391,
%U A081794 148096265277934997326846757550268707006396575812305676278686643630022889932579135326452726
%N A081794 Continued cotangent for Pi/4.
%D A081794 D. H. Lehmer, A cotangent analogue of continued fractions, Duke Math. J., 4 (1935), 323-340.
%F A081794 Pi/4 = cot(Sum_{n>=0} (-1)^n*acot(a(n))).
%F A081794 Let b(0) = Pi/4, b(n) = (b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))) then a(n) = floor(b(n)).
%o A081794 (PARI) \p900
%o A081794 bn=vector(100);
%o A081794 bn[1]=Pi/4;
%o A081794 b(n)=if(n<0,0,bn[n]);
%o A081794 for(n=2,10,bn[n]=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))));
%o A081794 a(n)=floor(b(n+1));
%Y A081794 Cf. A002666, A002667, A002668.
%K A081794 nonn
%O A081794 0,3
%A A081794 _Benoit Cloitre_, Apr 10 2003