%I #10 Jul 17 2024 19:04:46
%S 3,9,9,7,0,4,0,3,2,5,1,5,8,9,4,7,6,0,0,4,4,7,9,5,3,0,9,5,7,8,2,7,8,2,
%T 3,8,5,2,5,2,6,2,7,5,0,8,7,9,3,1,8,6,0,6,4,7,4,4,1,6,9,9,5,2,5,8,1,3,
%U 8,3,8,8,5,1,7,4,1,5,3,9,3,1,7,2,5,7
%N Decimal expansion of (3/13)*sqrt(3).
%F Equals Sum_{k>=0} tan(k*Pi/3)/3^k.
%e 0.39970403251589476004479530957827823852526275087931860...
%t s = Sum[Tan[k Pi/3]/3^k, {k, 0, Infinity}]
%t d = N[s, 100]
%t First[RealDigits[d]]
%t N[(3 Sqrt[3])/13, 100]
%t RealDigits[(3*Sqrt[3])/13,10,120][[1]] (* _Harvey P. Dale_, Jul 17 2024 *)
%o (Python)
%o from math import isqrt
%o def A372914(n): return isqrt(27*10**(n+1<<1)//169)%10 # _Chai Wah Wu_, Jul 08 2024
%Y Cf. A372912, A372913.
%K nonn,cons
%O 0,1
%A _Clark Kimberling_, Jul 01 2024