%I #24 Feb 19 2019 23:34:22

%S 1,1,1,1,3,3,3,45,45,45,945,945,4725,42525,42525,42525,1403325,

%T 49116375,49116375,1915538625,1915538625,1915538625,86199238125,

%U 86199238125,603394666875,30773128010625,30773128010625,1692522040584375,96473756313309375,96473756313309375

%N a(n) = (2n-1)!!/lcm{1,3,5,...,2n-1}.

%H Michael De Vlieger, <a href="/A025549/b025549.txt">Table of n, a(n) for n = 1..569</a>

%F a(n) = A001147(n)/A025547(n). - _Michel Marcus_, Dec 02 2014

%p seq(doublefactorial(2*n-1)/lcm(seq((2*k-1), k=1..n)), n=1..27) ; # _Johannes W. Meijer_, Jun 08 2009

%t L[ {x___} ] := LCM[ x ]; Table[ (2n-1)!!/L[ Range[ 1, 2n-1, 2 ] ], {n, 1, 50} ]

%t (* Second program: *)

%t Array[#!!/LCM @@ Range[1, #, 2] &[2 # - 1] &, 30] (* _Michael De Vlieger_, Feb 19 2019 *)

%o (PARI) a(n) = (((2*n)!/n!)/2^n)/lcm(vector(n, i, 2*i-1)); \\ _Michel Marcus_, Dec 02 2014

%Y Not always equal to the second left hand column of A161198 triangle divided by A074599. - _Johannes W. Meijer_, Jun 08 2009

%Y Cf. A196274 (run lengths of equal terms).

%K nonn,easy

%O 1,5

%A _Clark Kimberling_

%E Description corrected and sequence extended by _Erich Friedman_

%E More terms from _Michel Marcus_, Dec 02 2014