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A333240
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Decimal expansion of Product_{primes p == 2 (mod 3)} 1/(1 - 1/p^2).
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18
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1, 4, 1, 4, 0, 6, 4, 3, 9, 0, 8, 9, 2, 1, 4, 7, 6, 3, 7, 5, 6, 5, 5, 0, 1, 8, 1, 9, 0, 7, 9, 8, 2, 9, 3, 7, 9, 9, 0, 7, 6, 9, 5, 0, 6, 9, 3, 9, 3, 1, 6, 2, 1, 7, 5, 0, 3, 9, 9, 2, 4, 9, 6, 2, 4, 2, 3, 9, 2, 8, 1, 0, 6, 9, 9, 2, 0, 8, 8, 4, 9, 9, 4, 5, 3, 7, 5, 4, 8, 5, 8, 5, 0, 2, 4, 7, 5, 1, 1, 4, 2, 0, 0, 2
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OFFSET
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1,2
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COMMENTS
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The range of product are the primes of the form 3*k - 1 (A003627).
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LINKS
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FORMULA
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EXAMPLE
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1.414064390892147637565501819079829379907695069393162175039924962423928106992...
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MAPLE
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z := n -> Zeta(n)/Im(polylog(n, (-1)^(2/3))):
x := n -> (z(2^n)*(3^(2^n)-1)*sqrt(3)/2)^(1/2^n)/3:
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MATHEMATICA
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digits = 104; precision = digits + 10;
prodeuler[p_, a_, b_, expr_] := Product[If[a <= p <= b, expr, 1], {p, Prime[Range[PrimePi[a], PrimePi[b]]]}];
Lv3[s_] := prodeuler[p, 1, 2^(precision/s), 1/(1 - KroneckerSymbol[-3, p]*p^-s)] // N[#, precision]&;
Lv4[s_] := 2*Im[PolyLog[s, Exp[2*I*Pi/3]]]/Sqrt[3];
Lv[s_] := If[s >= 10000, Lv3[s], Lv4[s]];
gv[s_] := (1 - 3^(-s))*Zeta[s]/Lv[s];
pgv = Product[gv[2^n*2]^(2^-(n + 1)), {n, 0, 11}] // N[#, precision]&;
RealDigits[pgv, 10, digits][[1]]
z[n_] := Zeta[n]/Im[PolyLog[n, (-1)^(2/3)]];
x[n_] := (z[2^n] (3^(2^n) - 1) Sqrt[3]/2)^(1/2^n)/3;
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CROSSREFS
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KEYWORD
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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