OFFSET
1,2
COMMENTS
6/Pi = Volume of the cuboid (If L1>L2>L3) / Volume of the inscribed ellipsoid.
6/Pi = Volume of the cuboid (If L1>(L2=L3)) / Volume of the inscribed spheroid.
6/Pi = Volume of the regular hexahedron (or cube) / Volume of the inscribed Sphere.
6/Pi = 1 / Arc of 30 degrees.
6/Pi = Volume of the cuboid (If L1<(L2=L3)) / Volume of the inscribed spheroid.
6/Pi = Surface area of the regular hexahedron (or cube) / surface area of the inscribed sphere.
The Eisenstein series E_2(z) = 1 - 24*Sum_{n>=1} sigma(n)*q (cf. A006352) is quasimodular form satisfying E_2((a*z+b)/(c*z+d)) = (c*z+d)^2*E_2(z) - I*(6/Pi)*c*(c*z+d). See Proposition 6 in the link of D. Zagier for a proof. - Jianing Song, Mar 24 2026
LINKS
FORMULA
Equals Product_{k>=1} (2k+1)^3 / ( (2k)^2*(2k+3) ). - Federico Provvedi, Nov 09 2024
EXAMPLE
1.90985931710274402922660516047... .
MATHEMATICA
RealDigits[N[6/Pi, 200]] (* Erich Friedman, Mar 22 2008 *)
PROG
(PARI) 6/Pi \\ Charles R Greathouse IV, Dec 31 2011
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Omar E. Pol, Aug 26 2007, Nov 02 2007
EXTENSIONS
More terms from Erich Friedman, Mar 22 2008
STATUS
approved
