OFFSET
0,1
COMMENTS
The area of a deltoid formed by rolling a circle with radius 1/3 inside a unit-radius circle. - Amiram Eldar, Nov 16 2021
Volume shared by a sphere of radius 1 inscribed in a cube and one of the six pyramids inscribed in the cube. - Omar E. Pol, Sep 01 2024
LINKS
Ivan Panchenko, Table of n, a(n) for n = 0..1000
Eric Weisstein's World of Mathematics, Deltoid.
EXAMPLE
0.69813170079773183076947630739544508537714875541669...
MATHEMATICA
RealDigits[(2*Pi)/9, 10, 120][[1]] (* Harvey P. Dale, Aug 24 2013 *)
PROG
(PARI) 2*Pi/9 \\ Michel Marcus, Nov 16 2021
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
STATUS
approved