A374813 Decimal expansion of Sum_{k>=0} cos(2k*Pi/5)/2^k.

8, 9, 8, 5, 1, 9, 4, 1, 8, 2, 6, 6, 1, 1, 8, 8, 5, 6, 2, 7, 7, 8, 6, 3, 2, 4, 2, 0, 3, 5, 3, 8, 4, 3, 3, 3, 9, 7, 2, 9, 3, 3, 1, 4, 6, 4, 3, 2, 8, 1, 5, 7, 6, 0, 8, 5, 1, 8, 1, 7, 6, 0, 8, 6, 4, 8, 8, 9, 6, 1, 7, 3, 8, 2, 1, 1, 8, 4, 1, 0, 8, 0, 3, 6, 1, 8

Offset

0,1

Links

Table of n, a(n) for n=0..85.

Formula

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

Equals Sum_{k>=0} cos(8 k*Pi/5)/2^k.

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

Equals 2 - 2*A373017. - R. J. Mathar, Aug 27 2024

Example

0.8985194182661188562778632420353843339729...

Mathematica

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

Crossrefs

Cf. A373021 (includes guide to related sequences).

Sequence in context: A019738 A236098 A135466 * A265296 A230154 A338856

Adjacent sequences: A374810 A374811 A374812 * A374814 A374815 A374816

Keyword

nonn,cons

Author

Clark Kimberling, Jul 20 2024

Status

approved