A197808 Decimal expansion of x>0 having x^2 = 4*cos(x).

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

Offset

1,2

Comments

See A197737 for a guide to related sequences. The Mathematica program includes a graph.

Links

Table of n, a(n) for n=1..99.

Index entries for transcendental numbers.

Example

1.201538299340575111481508166568850491060835...

Mathematica

a = 1; b = 0; c = 4;
f[x_] := a*x^2 + b*x; g[x_] := c*Cos[x]
Plot[{f[x], g[x]}, {x, -1.5, 1.5}]
r1 = x /. FindRoot[f[x] == g[x], {x, 1.2, 1.3}, WorkingPrecision -> 110]
RealDigits[r1] (* A197808 *)

Prog

(PARI) solve(x=1, 2, x^2-4*cos(x)) \\ Charles R Greathouse IV, May 17 2026

Crossrefs

Cf. A197737.

Sequence in context: A037186 A343239 A004483 * A085650 A343751 A201910

Adjacent sequences: A197805 A197806 A197807 * A197809 A197810 A197811

Keyword

nonn,cons

Author

Clark Kimberling, Oct 20 2011

Status

approved