This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A374815 #4 Jul 22 2024 15:28:42
%S A374815 6,8,2,1,2,5,7,4,3,0,2,4,2,0,3,7,2,4,3,6,7,2,9,8,0,4,8,2,8,7,1,9,6,3,
%T A374815 1,1,1,8,8,3,5,7,1,7,6,1,4,7,8,2,9,4,0,0,4,3,8,5,0,4,9,7,1,9,9,6,2,6,
%U A374815 5,1,1,6,5,0,1,3,9,6,5,3,7,1,2,5,1,0
%N A374815 Decimal expansion of Sum_{k>=0} cos(4k*Pi/5)/2^k.
%F A374815 Equals (49 - 3*sqrt(5))/62.
%F A374815 Equals Sum_{k>=0} cos(6 k*Pi/5)/2^k.
%F A374815 Minimal polynomial: 19 - 49 x + 31 x^2.
%e A374815 0.6821257430242037243672980482871963111...
%t A374815 {b, m, h} = {2, 5, 4}; s = Sum[Cos[ h k Pi/m]/b^k, {k, 0, Infinity}]
%t A374815 d = N[s, 100]
%t A374815 First[RealDigits[d], 100]
%Y A374815 Cf. A373021 (includes guide to related sequences).
%K A374815 nonn,cons
%O A374815 0,1
%A A374815 _Clark Kimberling_, Jul 20 2024