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A081783
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Continued cotangent for zeta(2)=Pi^2/6.
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0
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1, 4, 172, 181307, 241328833528, 824652019956267685427678, 768422457901766762303892554138930904416139509281, 2110688056630901907060877896737932376507936264268382076456539236145849709148481095915090382331184
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| Pi^2/6=cot(sum(n>=0, n, (-1)^n*acot(a(n))); let b(0)=Pi^2/6, 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
| (PARI) ?bn=vector(100); b(n)=if(n<0, 0, bn[n]); bn[1]=Pi^2/6; ?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
| Cf. A001620, A002666, A002667.
Sequence in context: A057140 A195631 A145245 * A006433 A113254 A127606
Adjacent sequences: A081780 A081781 A081782 * A081784 A081785 A081786
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KEYWORD
| nonn
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AUTHOR
| Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 10 2003
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