A196398 - OEIS

%I #11 Jul 30 2021 02:36:32

%S 9,0,4,7,8,8,2,1,7,8,7,3,0,1,8,8,5,3,4,7,4,0,2,1,3,5,9,9,3,7,0,4,3,4,

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

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

%N Decimal expansion of the positive number x satisfying e^x=4*cos(x).

%e 0.90478821787301885347402135993704348827...

%t Plot[{E^x, 2 Cos[x], 3 Cos[x], 4 Cos[x]}, {x, 0, Pi/2}]

%t t = x /.

%t   FindRoot[E^x == 2 Cos[x], {x, .5, .6}, WorkingPrecision -> 100]; RealDigits[t]  (* A196396 *)

%t t = x /.

%t   FindRoot[E^x == 3 Cos[x], {x, .7, .8}, WorkingPrecision -> 100]; RealDigits[t]  (* A196397 *)

%t t = x /.

%t   FindRoot[E^x == 4 Cos[x], {x, .8, 1.0}, WorkingPrecision -> 100]; RealDigits[t]  (* A196398 *)

%t t = x /.

%t   FindRoot[E^x == 5 Cos[x], {x, .8, 1.0}, WorkingPrecision -> 100]; RealDigits[t]  (* A196399 *)

%t t = x /.

%t   FindRoot[E^x == 6 Cos[x], {x, 1.0, 1.1}, WorkingPrecision -> 100]; RealDigits[t]  (* A196400 *)

%K nonn,cons

%O 0,1

%A _Clark Kimberling_, Oct 02 2011

%E a(100) corrected by _Georg Fischer_, Jul 30 2021