The On-Line Encyclopedia of Integer Sequences (OEIS)

A081785 revision #5

A081785

Continued cotangent for log(2).

0, 1, 5, 55, 14187, 314681540, 254841004490568887, 116515298784769863036311841843812470, 16752745298264669840183664790312981823804061660537952218518280274360024

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OFFSET

0,3

LINKS

Table of n, a(n) for n=0..8.

FORMULA

log(2)=cot(sum(n>=0,n,(-1)^n*acot(a(n))); let b(0)=log(2), 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]=log(2); ?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. A001620, A002666, A002667.

Sequence in context: A082780 A063855 A376767 * A144996 A129440 A045729

Adjacent sequences: A081782 A081783 A081784 * A081786 A081787 A081788

KEYWORD

cons,nonn,new

AUTHOR

Benoit Cloitre (abmt(AT)wanadoo.fr), Apr 10 2003

STATUS

approved