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 A081792 #13 Apr 24 2025 06:12:54
%S A081792 1,4,28,898,865865,6558406221253,369641727028862496144018420,
%T A081792 168218383805281752399017936550348552720479497871513674,
%U A081792 46139813370820669084709611625366168409170012365100187639338625228748249752136723842763775088752136299316085
%N A081792 Continued cotangent for cosh(1).
%D A081792 D. H. Lehmer, A cotangent analogue of continued fractions, Duke Math. J., 4 (1935), 323-340.
%F A081792 cosh(1) = cot(Sum_{n>=0} (-1)^n*acot(a(n))).
%F A081792 Let b(0) = cosh(1), b(n) = (b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))) then a(n) = floor(b(n)).
%o A081792 (PARI) \p900
%o A081792 bn=vector(100);
%o A081792 bn[1]=cosh(1);
%o A081792 b(n)=if(n<0,0,bn[n]);
%o A081792 for(n=2,10,bn[n]=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))));
%o A081792 a(n)=floor(b(n+1));
%Y A081792 Cf. A002666, A002667, A002668.
%K A081792 nonn
%O A081792 0,2
%A A081792 _Benoit Cloitre_, Apr 10 2003