A196817 Decimal expansion of the least x>0 satisfying 1/(1+x^2)=2*cos(x).
1, 4, 0, 1, 2, 6, 9, 2, 0, 7, 5, 9, 9, 9, 5, 7, 9, 4, 2, 9, 2, 7, 1, 8, 7, 2, 4, 3, 7, 9, 0, 8, 3, 4, 1, 9, 1, 5, 3, 0, 8, 8, 2, 8, 6, 5, 4, 5, 3, 3, 6, 0, 2, 6, 0, 3, 7, 9, 1, 7, 8, 2, 5, 0, 7, 8, 6, 3, 1, 6, 4, 0, 0, 0, 4, 3, 1, 7, 1, 7, 3, 3, 3, 7, 3, 4, 8, 3, 3, 1, 2, 5, 9, 5, 7, 5, 7, 7, 9, 3
Offset: 1
Examples
x=1.401269207599957942927187243790834191530882865453360260...
Crossrefs
Cf. A196914.
Programs
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Mathematica
Plot[{1/(1 + x^2), Cos[x], 2 Cos[x], 3 Cos[x], 4 Cos[x]}, {x, 0, 2}] t = x /. FindRoot[1 == (1 + x^2) Cos[x], {x, 1, 1.5}, WorkingPrecision -> 100] RealDigits[t] (* A196816 *) t = x /. FindRoot[1 == 2 (1 + x^2) Cos[x], {x, 1, 1.6}, WorkingPrecision -> 100] RealDigits[t] (* A196817 *) t = x /. FindRoot[1 == 3 (1 + x^2) Cos[x], {x, 1, 1.6}, WorkingPrecision -> 100] RealDigits[t] (* A196818 *) t = x /. FindRoot[1 == 4 (1 + x^2) Cos[x], {x, 1, 1.6}, WorkingPrecision -> 100] RealDigits[t] (* A196819 *) t = x /. FindRoot[1 == 5 (1 + x^2) Cos[x], {x, 1, 1.6}, WorkingPrecision -> 100] RealDigits[t] (* A196820 *) t = x /. FindRoot[1 == 6 (1 + x^2) Cos[x], {x, 1, 1.6}, WorkingPrecision -> 100] RealDigits[t] (* A196821 *)