%I #11 Jul 08 2024 08:53:39
%S 4,9,4,8,7,1,6,5,9,3,0,5,3,9,3,5,1,2,4,3,6,4,1,3,2,4,0,4,3,0,2,4,9,2,
%T 4,7,6,9,7,9,4,4,3,5,8,2,3,1,5,3,7,3,2,2,3,0,1,6,5,9,1,3,6,9,8,6,2,6,
%U 6,5,7,6,2,5,9,6,5,7,1,5,3,4,5,1,7,5
%N Decimal expansion of (2/7)*sqrt(3).
%F Equals Sum_{k>=0} tan(k*Pi/3)/2^k.
%e 0.494871659305393512436413240430249247697944358...
%t s = Sum[Tan[k Pi/3]/2^k, {k, 0, Infinity}]
%t d = N[s, 100]
%t First[RealDigits[d]]
%t N[(2 Sqrt[3])/7, 100]
%o (Python)
%o from math import isqrt
%o def A372912(n): return isqrt(12*10**(n+1<<1)//49)%10 # _Chai Wah Wu_, Jul 08 2024
%Y Cf. A372913, A372914.
%K nonn,cons
%O 0,1
%A _Clark Kimberling_, Jul 01 2024