A365165 Length of the perimeter of the regular 9-gon with unit circumradius.

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

Offset

1,1

Links

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

Index entries for algebraic numbers, degree 6.

Formula

Equals 9*A272488.

Minimal polynomial: x^6 - 486*x^4 + 59049*x^2 - 1594323. - Amiram Eldar, Jun 06 2026

Example

6.1563625798620371947937930642806724537...

Mathematica

First[RealDigits[18*Sin[Pi/9], 10, 100]] (* Paolo Xausa, Mar 19 2024 *)

Prog

(PARI) 18*sin(Pi/9) \\ Charles R Greathouse IV, May 11 2026
(PARI) polrootsreal(x^6 - 486*x^4 + 59049*x^2 - 1594323)[4] \\ Charles R Greathouse IV, May 11 2026

Crossrefs

Cf. A019845 (5-gon), A010487 (4-gon), A365163 (7-gon), A365164 (8-gon), A272488 (edge length).

Sequence in context: A372065 A370424 A325313 * A019847 A021946 A257704

Adjacent sequences: A365162 A365163 A365164 * A365166 A365167 A365168

Keyword

nonn,cons,changed

Author

R. J. Mathar, Aug 24 2023

Status

approved