A387443 Decimal expansion of cos(Pi/22).

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

Offset

0,1

Links

Paolo Xausa, Table of n, a(n) for n = 0..10000

Index entries for algebraic numbers, degree 10

Formula

Equals sin(5*Pi/11) = sqrt( (A387440+1)/2 ).

Largest of the 10 real-valued roots of 1024*x^10 -2816*x^8 +2816*x^6 -1232*x^4 +220*x^2 -11 =0.

Example

0.9898214418809327323760920377767187873765193719487...

Mathematica

First[RealDigits[Cos[Pi/22], 10, 100]] (* Paolo Xausa, Nov 17 2025 *)

Crossrefs

Cf. A019689.

Sequence in context: A309642 A146484 A116695 * A109940 A275106 A010549

Adjacent sequences: A387440 A387441 A387442 * A387444 A387445 A387446

Keyword

nonn,cons,easy

Author

R. J. Mathar, Aug 29 2025

Status

approved