A375070 Decimal expansion of the sagitta of a regular octagon with unit side length.

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

Offset

-1,1

Links

Paolo Xausa, Table of n, a(n) for n = -1..10000

Eric Weisstein's World of Mathematics, Regular Polygon.

Eric Weisstein's World of Mathematics, Sagitta.

Index entries for algebraic numbers, degree 4.

Formula

Equals tan(Pi/16)/2 = A343060/2.

Equals A285871 - A174968.

Minimal polynomial: 16*x^4 + 32*x^3 - 24*x^2 - 8*x + 1. - Amiram Eldar, Jun 05 2026

Example

0.09945618368982900345579881132233811429892525066...

Mathematica

First[RealDigits[Tan[Pi/16]/2, 10, 100]]

Prog

(PARI) tan(Pi/16)/2 \\ Charles R Greathouse IV, Feb 05 2025

Crossrefs

Cf. A285871 (circumradius), A174968 (apothem), A090488 (area).

Cf. sagitta of other polygons with unit side length: A020769 (triangle), A174968 (square), A375068 (pentagon), A375069 (hexagon), A374972 (heptagon), A375153 (9-gon), A375189 (10-gon), A375192 (11-gon), A375194 (12-gon).

Cf. A343060.

Sequence in context: A346585 A117023 A388885 * A013668 A143302 A202540

Adjacent sequences: A375067 A375068 A375069 * A375071 A375072 A375073

Keyword

nonn,cons,easy

Author

Paolo Xausa, Jul 30 2024

Status

approved