A387449 Decimal expansion of cos(Pi/31).

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

Offset

0,1

Links

A.H.M. Smeets, Table of n, a(n) for n = 0..20000

R. J. Mathar, Reduction formulas of the cosine of integer fractions of pi, (2008) vixra:2210.0026.

Index entries for algebraic numbers, degree 15

Formula

Equals sin(29*Pi/62).

Largest of the 15 real-valued roots of 32768*x^15 -16384*x^14 -114688*x^13 +53248*x^12 +159744*x^11 -67584*x^10 -112640*x^9 +42240*x^8 +42240*x^7 -13440*x^6 -8064*x^5 +2016*x^4 +672*x^3 -112*x^2 -16*x +1 =0.

Example

0.99486932339189514632135330988371949300396522229124...

Mathematica

First[RealDigits[Cos[Pi/31], 10, 100]] (* Paolo Xausa, Nov 18 2025 *)

Crossrefs

Cf. A132700.

Sequence in context: A143302 A202540 A218708 * A010550 A392301 A192106

Adjacent sequences: A387446 A387447 A387448 * A387450 A387451 A387452

Keyword

nonn,cons,easy

Author

R. J. Mathar, Aug 29 2025

Status

approved