OFFSET
0,2
REFERENCES
A. P. Prudnikov, Yu. A. Brychkov, and O. I. Marichev, Integrals and Series, Vol. 1 (Overseas Publishers Association, Amsterdam, 1986), p. 757, section 6.2.4, formula 2.
LINKS
Eric Weisstein's World of Mathematics, Sinc Function
FORMULA
Pi/(2K), where K is given by A051762.
EXAMPLE
0.180550541849851923912372592930506075911340235805618395412359992217663184593...
MAPLE
evalf(Pi/(2*(product(sec(Pi/k), k = 3..infinity))), 104); # Vaclav Kotesovec, Aug 16 2015
MATHEMATICA
digits = 102; $MaxExtraPrecision = 100; exactEnd = 100; seriesOrder = 60; f[n_] := Log[Sinc[2Pi/(2n + 1)]]; exactSum = Sum[f[n], {n, 1, exactEnd}]; se = Series[f[n], {n, Infinity, seriesOrder}] // Normal; extraSum = Sum[se, {n, exactEnd + 1, Infinity}]; RealDigits[Exp[exactSum + extraSum ], 10, digits] // First (* Jean-François Alcover, Feb 07 2013 *)
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Eric W. Weisstein, Apr 18 2006
EXTENSIONS
Last digit corrected by Vaclav Kotesovec, Aug 16 2015
STATUS
approved