The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A081789 Continued cotangent for cos(1). 0
 0, 1, 3, 31, 1896, 4466398, 51545652359935, 7892797673015743066290382811, 79208317703482281896053478218775642522933780224074809198, 195824124605155340760338534459689354174423866004140103635128465652592661899008938733448659610261796713081609084855 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 REFERENCES D. H. Lehmer, A cotangent analogue of continued fractions, Duke Math. J., 4 (1935), 323-340. LINKS FORMULA cos(1)=cot(sum(n>=0, n, (-1)^n*acot(a(n))); let b(0)=cos(1), b(n)=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1)) then a(n)=floor(b(n)). PROG (PARI) ?bn=vector(100); b(n)=if(n<0, 0, bn[n]); bn[1]=cos(1); ?for(n=2, 10, bn[n]=(b(n-1)*floor(b(n-1))+1)/(b(n-1)-floor(b(n-1)))) ?a(n)=floor(b(n+1)) CROSSREFS Cf. A002666, A002667, A002668. Sequence in context: A194937 A141153 A144906 * A066976 A172645 A201604 Adjacent sequences:  A081786 A081787 A081788 * A081790 A081791 A081792 KEYWORD nonn AUTHOR Benoit Cloitre, Apr 10 2003 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified November 29 21:32 EST 2021. Contains 349416 sequences. (Running on oeis4.)