A373024 Decimal expansion of Sum_{k>=0} sin(4k*Pi/5)/2^k.

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

Offset

0,2

Links

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

Formula

Equals sqrt((10 - 2 sqrt(5)]/(12 + 2 sqrt(5)).

Equals (-1)*Sum_{k>=0} sin(6 k*Pi/5)/2^k.

Minimal polynomial: 5 - 265 x^2 + 961 x^4.

Example

0.14273443441658095225471374294933839312078514...

Mathematica

{b, m, h} = {2, 5, 4}; s = Sum[Sin[ 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: A198994 A368664 A182364 * A021238 A222622 A161179

Adjacent sequences: A373021 A373022 A373023 * A373025 A373026 A373027

Keyword

nonn,cons

Author

Clark Kimberling, Jul 20 2024

Status

approved