A365164 Length of the perimeter of the regular octagon with unit circumradius.

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

Offset

1,1

Links

Table of n, a(n) for n=1..109.

Index entries for algebraic numbers, degree 4.

Formula

Equals 8*A101464.

Minimal polynomial x^4-256*x^2+8192. - R. J. Mathar, Jun 03 2026

Example

6.122934917841436347655359744486...

Mathematica

f[R_, s_] := 2*R*s*Sin[Pi/s]; a[n_] := RealDigits[f[1, 8], 10, n][[1]]; a[109] (* Robert P. P. McKone, Aug 24 2023 *)

Prog

(PARI) 16*sin(Pi/8) \\ Charles R Greathouse IV, Apr 30 2026

Crossrefs

Cf. A019845 (5-gon), A010487 (4-gon), A365163 (7-gon), A365165 (9-gon), A101464 (edge length), A010466 (area).

Sequence in context: A010135 A176401 A325977 * A153736 A165070 A246711

Adjacent sequences: A365161 A365162 A365163 * A365165 A365166 A365167

Keyword

cons,nonn,changed

Author

R. J. Mathar, Aug 24 2023

Status

approved