Pi/12 - 1/4.
1, 1, 7, 9, 9, 3, 8, 7, 7, 9, 9, 1, 4, 9, 4, 3, 6, 5, 3, 8, 5, 5, 3, 6, 1, 5, 2, 7, 3, 2, 9, 1, 9, 0, 7, 0, 1, 6, 4, 3, 0, 7, 8, 3, 2, 8, 1, 2, 5, 8, 8, 1, 8, 4, 1, 4, 5, 7, 8, 7, 1, 6, 0, 2, 5, 6, 5, 1, 3, 6, 7, 1, 9, 0, 5, 1, 7, 4, 1, 6, 5, 5, 2, 3, 3, 6, 2, 3, 5, 4, 4, 5, 1, 7, 6, 4, 2, 2, 3, 3, 1, 8, 4, 5, 6, 7
-1
When an 12-gon is inscibed in a unit circle, this is the area of one of the 12 segments of the circle not in the 12-gon.
T. D. Noe, Plot of 1000 terms
T. D. Noe, Table of 1000 terms
Eric W. Weisstein, Circular segment
Wikipedia, Circular segment
This is Pi/n - sqrt((p^2+q^2)*((p-1)^2+q^2)), where p = (1 + cos(2*Pi/n))/2 and q = sin(2*Pi/n)/2 for n=12.
The number is 0.011799387799149436538553615273291907016430783281….
(Mma) RealDigits[Pi/12 - 1/4], 10, 105][[1]]
Cf. S000236, S000237, S000238, S000243-S000248, S000250, S000251.
nonn,cons,nice
T. D. Noe, Sep 05 2014