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 A081791 #14 Apr 24 2025 06:12:58
%S A081791 1,12,361,6098638,40523300374005,2249947521757014011818803347,
%T A081791 23934989997298328927868650983263126279480229971908985849,
%U A081791 2858972935444266747494645602151444724302966656792002957565134720098726922500919331865545624811189334200411357440
%N A081791 Continued cotangent for sinh(1).
%D A081791 D. H. Lehmer, A cotangent analogue of continued fractions, Duke Math. J., 4 (1935), 323-340.
%F A081791 sinh(1) = cot(Sum_{n>=0} (-1)^n*acot(a(n))).
%F A081791 Let b(0) = sinh(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 A081791 (PARI) \p900
%o A081791 bn=vector(100);
%o A081791 bn[1]=sinh(1);
%o A081791 b(n)=if(n<0,0,bn[n]);
%o A081791 for(n=2,10,bn[n]=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1))));
%o A081791 a(n)=floor(b(n+1));
%Y A081791 Cf. A002666, A002667, A002668.
%K A081791 nonn
%O A081791 0,2
%A A081791 _Benoit Cloitre_, Apr 10 2003