|
|
A002867
|
|
a(n) = binomial(n,floor(n/2))*(n+1)!.
(Formerly M2035 N0806)
|
|
3
|
|
|
1, 2, 12, 72, 720, 7200, 100800, 1411200, 25401600, 457228800, 10059033600, 221298739200, 5753767219200, 149597947699200, 4487938430976000, 134638152929280000, 4577697199595520000, 155641704786247680000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,2
|
|
REFERENCES
|
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
|
|
LINKS
|
|
|
FORMULA
|
E.g.f.: 1/(sqrt(1+2*x)*(1-2*x)^(3/2)) = 1/(sqrt(1-4*x^2)*(1-2*x)). - Paul Barry, Jul 22 2005
Conjecture: a(n) - 2*a(n-1) - 4*n*(n-1)*a(n-2) = 0. - R. J. Mathar, Nov 24 2012
|
|
MATHEMATICA
|
Table[Binomial[n, Floor[n/2]](n+1)!, {n, 0, 20}] (* Harvey P. Dale, Sep 04 2018 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
|
|
EXTENSIONS
|
|
|
STATUS
|
approved
|
|
|
|