A021148 Decimal expansion of 1/144.

0, 0, 6, 9, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4

Offset

0,3

Comments

25/36 = 100 * (1/144) = 0.694444... is the probability that the convex hull of four points independently and uniformly selected at random in the interior of a square is a quadrilateral. - Amiram Eldar, Apr 02 2026

Links

Table of n, a(n) for n=0..98.

Eric Weisstein's MathWorld, Sylvester's Four-Point Problem.

Index entries for linear recurrences with constant coefficients, signature (1).

Formula

G.f.: x^2*(6 + 3*x - 5*x^2)/(1 - x). - Chai Wah Wu, Jun 21 2016

Mathematica

PadLeft[First@ #, Abs@ Last@ # + Length@ First@ #] &@ RealDigits[N[1/144, 120]] (* Bruno Berselli, Jun 21 2016 *)
Join[{0, 0}, RealDigits[1/144, 10, 120][[1]]] (* Harvey P. Dale, Oct 30 2022 *)

Crossrefs

Sequence in context: A155784 A143735 A216117 * A385493 A269981 A133749

Adjacent sequences: A021145 A021146 A021147 * A021149 A021150 A021151

Keyword

nonn,cons,easy

Author

N. J. A. Sloane

Status

approved