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A081794
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Continued cotangent for Pi/4.
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0
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0, 1, 8, 211, 114681, 118304381067, 14093169772574392414247, 233069007722838136376547872705625127588988391, 148096265277934997326846757550268707006396575812305676278686643630022889932579135326452726
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OFFSET
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0,3
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REFERENCES
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D. H. Lehmer, A cotangent analogue of continued fractions, Duke Math. J., 4 (1935), 323-340.
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LINKS
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FORMULA
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Pi/4=cot(sum(n>=0, n, (-1)^n*acot(a(n))); 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))
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PROG
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(PARI) ?bn=vector(100); b(n)=if(n<0, 0, bn[n]); bn[1]=Pi/4; ?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))
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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