OFFSET
1,5
LINKS
Michael De Vlieger, Table of n, a(n) for n = 1..569
FORMULA
MAPLE
seq(doublefactorial(2*n-1)/lcm(seq((2*k-1), k=1..n)), n=1..27) ; # Johannes W. Meijer, Jun 08 2009
MATHEMATICA
L[ {x___} ] := LCM[ x ]; Table[ (2n-1)!!/L[ Range[ 1, 2n-1, 2 ] ], {n, 1, 50} ]
(* Second program: *)
Array[#!!/LCM @@ Range[1, #, 2] &[2 # - 1] &, 30] (* Michael De Vlieger, Feb 19 2019 *)
PROG
(PARI) a(n) = (((2*n)!/n!)/2^n)/lcm(vector(n, i, 2*i-1)); \\ Michel Marcus, Dec 02 2014
CROSSREFS
Not always equal to the second left hand column of A161198 triangle divided by A074599. - Johannes W. Meijer, Jun 08 2009
Cf. A196274 (run lengths of equal terms).
KEYWORD
nonn,easy
AUTHOR
EXTENSIONS
Description corrected and sequence extended by Erich Friedman
More terms from Michel Marcus, Dec 02 2014
STATUS
approved