A089512 - OEIS

%I #13 Mar 15 2018 04:22:04

%S 1,2,1,18,6,360,90,12600,2520,680400,113400,52390800,7484400,

%T 5448643200,681080400,735566832000,81729648000,125046361440000,

%U 12504636144000,26134689540960000,2375880867360000,6585941764321920000

%N Denominators used in the computation of the column sequences of array A078739 ((2,2)-Stirling2).

%C See A089511 for the column sequence computation of A078739.

%F a(n) = lcm(seq(denominator(b(n, m)), m=1..n-1)), n>=2, where b(n, m) is defined like A089511(n, m) but without the factor D(n) and lcm stands for the least common multiple of a set of numbers.

%F a(n) = (sqrt(2)*n!/(8*2^(n/2)))*((n^2+4n+2*sqrt(2)+3)-(n^2+4n-2*sqrt(2)+3)*(-1)^n) [offset 0]. - _Paul Barry_, Sep 04 2007

%K nonn,easy

%O 2,2

%A _Wolfdieter Lang_, Dec 01 2003