A197149 Decimal expansion of the shortest distance from the x axis through (1,1) to the line y=3x.

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

Offset

1,2

Comments

The shortest segment from one side of an angle T through a point P inside T is called the Philo line of P in T. For discussions and guides to related sequences, see A197032, A197008 and A195284.

Links

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

Example

length of Philo line:    1.999158399580...
endpoint on x axis:    (1.60479, 0); see A197148
endpoint on line y=3x: (0.570212, 1.71064)

Mathematica

f[t_] := (t - k*t/(k + m*t - m*h))^2 + (m*k*t/(k + m*t - m*h))^2;
g[t_] := D[f[t], t]; Factor[g[t]]
p[t_] := h^2 k + k^3 - h^3 m - h k^2 m - 3 h k t + 3 h^2 m t + 2 k t^2 - 3 h m t^2 + m t^3
m = 3; h = 1; k = 1; (* slope m, point (h, k) *)
t = t1 /. FindRoot[p[t1] == 0, {t1, 1, 2}, WorkingPrecision -> 100]
RealDigits[t] (* A197148 *)
{N[t], 0} (* endpoint on x axis *)
{N[k*t/(k + m*t - m*h)],
N[m*k*t/(k + m*t - m*h)]} (* endpt on line y=3x *)
d = N[Sqrt[f[t]], 100]
RealDigits[d]  (* A197149 *)
Show[Plot[{k*(x - t)/(h - t), m*x}, {x, 0, 2}],
ContourPlot[(x - h)^2 + (y - k)^2 == .001, {x, 0, 4}, {y, 0, 3}], PlotRange -> {0, 2}, AspectRatio -> Automatic]

Crossrefs

Cf. A197032, A197049, A197008, A195284.

Sequence in context: A339745 A346929 A346927 * A274031 A111623 A229985

Adjacent sequences: A197146 A197147 A197148 * A197150 A197151 A197152

Keyword

nonn,cons

Author

Clark Kimberling, Oct 11 2011

Status

approved