A103308 - OEIS

%I #11 Apr 14 2022 05:33:53

%S 18,135,135,1701,20412,1458,32805,1082565,144342,2302911,48361131,

%T 18600435,191318760,975725676,243931419,2453663097,14721978582,

%U 903981141,268482398877,2646469360359,962352494676,4707158941350

%N Reduced denominators of the central moments of the distribution of random line segments picked on a unit line segment.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/LineLinePicking.html">Line Line Picking</a>.

%F a(n) = denominator((2^(n+3)+(-1)^n*2*(3*n+5))/((n+1)*(n+2)*3^(n+2))). - _Amiram Eldar_, Apr 14 2022

%e 1/18, 1/135, 1/135, 4/1701, 31/20412, 1/1458, 13/32805, 224/1082565, ...

%t a[n_] := Denominator[(2^(n + 3) + (-1)^n*2*(3*n + 5))/((n + 1)*(n + 2)*3^(n + 2))]; Array[a, 20, 2] (* _Amiram Eldar_, Apr 14 2022 *)

%Y Cf. A103307 (numerators).

%K nonn,frac

%O 2,1

%A _Eric W. Weisstein_, Jan 28 2005