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Search: id:A048581
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| A048581 |
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Numerators of b(n) = 1/16^n*(4/(8*n+1)-2/(8*n+4)-1/(8*n+5)-1/(8*n+6)). |
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+0
3
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| 47, 53, 829, 79, 857, 1901, 5273, 97, 1787, 5563, 4519, 4057, 19139, 743, 25681, 229, 3687, 18647, 8329, 3853, 51067, 28069, 20483, 335, 72791, 4379, 85093, 22901, 6557, 52673, 112577, 2501, 127759, 13571, 15989, 38083, 161003, 28319, 35813
(list; graph; listen)
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OFFSET
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0,1
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COMMENT
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Sum( k>=0, b(k) ) = Pi was the first BBP formula for Pi (Bayley-Borwein-Plouffe in 1995). Allows one to extract any specified binary digit of Pi.
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LINKS
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B. Gourevitch, L'univers de Pi
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FORMULA
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sum( k>=0, b(k) ) = Pi
a(n)=numerator((1/16)^n*sum(i=1,4,((-1)^(ceil(4/(2*i))))*(floor(4/i))/(8*n+i+floor(sqrt(i-1))*(floor(sqrt(i-1))+1)))) [From Alexander R. Povolotsky (pevnev(AT)juno.com), Aug 31 2009]
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PROGRAM
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(PARI) a(n)=numerator(1/16^n*(4/(8*n+1)-2/(8*n+4)-1/(8*n+5)-1/(8*n+6)))
(PARI) a(n)=numerator((1/16)^n*sum(i=1, 4, ((-1)^(ceil(4/(2*i))))*(floor(4/i))/(8*n+i+floor(sqrt(i-1))*(floor(sqrt(i-1))+1)\ ))) [From Alexander R. Povolotsky (pevnev(AT)juno.com), Aug 31 2009]
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CROSSREFS
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Cf. A066968.
Sequence in context: A141279 A155139 A106279 this_sequence A045140 A104852 A061758
Adjacent sequences: A048578 A048579 A048580 this_sequence A048582 A048583 A048584
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KEYWORD
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easy,frac,nonn
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Aug 13 2002
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