A374815 Decimal expansion of Sum_{k>=0} cos(4k*Pi/5)/2^k.

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, 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, 5, 1, 1, 6, 5, 0, 1, 3, 9, 6, 5, 3, 7, 1, 2, 5, 1, 0

Offset: 0

Author

Clark Kimberling, Jul 20 2024

Keywords

• nonn
• cons

Examples

			0.6821257430242037243672980482871963111...
		

Crossrefs

Cf. A373021 (includes guide to related sequences).

Programs

Mathematica

{b, m, h} = {2, 5, 4}; s = Sum[Cos[ h  k  Pi/m]/b^k, {k, 0, Infinity}]
d = N[s, 100]
First[RealDigits[d], 100]

Formula

Equals (49 - 3*sqrt(5))/62.

Equals Sum_{k>=0} cos(6 k*Pi/5)/2^k.

Minimal polynomial: 19 - 49 x + 31 x^2.