A387446 Decimal expansion of cos(Pi/26).

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

Offset

0,1

Links

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

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

Index entries for algebraic numbers, degree 12

Formula

Equals sin(6*Pi/13) = sqrt( (A387441+1)/2 ).

Largest of the 12 real-valued roots of 4096*x^12 -13312*x^10 +16640*x^8 -9984*x^6 +2912*x^4 -364*x^2 +13 = 0.

Example

0.992708874098053992800751649492520179343675632970...

Mathematica

First[RealDigits[Cos[Pi/26], 10, 100]] (* Paolo Xausa, Nov 17 2025 *)

Crossrefs

Sequence in context: A388893 A019892 A275710 * A110639 A254273 A011211

Adjacent sequences: A387443 A387444 A387445 * A387447 A387448 A387449

Keyword

nonn,cons,easy

Author

R. J. Mathar, Aug 29 2025

Status

approved