A387442 Decimal expansion of cos(Pi/19).

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

Offset: 0

Author

R. J. Mathar, Aug 29 2025

Keywords

• nonn
• cons
• new

Examples

			0.98636130340272237360...
		

Links

• R. J. Mathar, Reduction formulas of the cosine of integer fractions of pi, (2008) vixra:2210.0026
• Index entries for algebraic numbers, degree 9

Crossrefs

Cf. A019686.

Formula

Equals sin(17*Pi/38).

Largest root of 512*x^9 -256*x^8 -1024*x^7 +448*x^6 +672*x^5 -240*x^4 -160*x^3 +40*x^2 +10*x -1 =0.