OFFSET
1,1
LINKS
Bela Bollobas, The number of 1-factors in 2k-connected graphs, J. Combin. Theory Ser. B 25 (1978), no. 3, 363--366. MR0516268 (80m:05060). See Eq. (2).
FORMULA
(n-1)*a(n) =n*(2n-1)*a(n-1), n>2. - R. J. Mathar, Mar 27 2012
MATHEMATICA
a[n_] := If[n == 1, 2, (4n/3)*(2n - 1)!!]; Array[a, 20] (* Amiram Eldar, Dec 01 2018 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Mar 27 2012
STATUS
approved