OFFSET
0,1
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..222
FORMULA
Equals (2*n+4) * A001818(n+1).
Equals (n+2)!*(n+1)!*binomial(2*n+2, n+1)^2/2^(2*n+1). - G. C. Greubel, Sep 24 2019
MAPLE
seq((n+2)!*(n+1)!*binomial(2*n+2, n+1)^2/2^(2*n+1), n=0..20); # G. C. Greubel, Sep 24 2019
MATHEMATICA
Table[(n+2)!*(n+1)!*Binomial[2*n+2, n+1]^2/2^(2*n+1), {n, 0, 20}] (* G. C. Greubel, Sep 24 2019 *)
PROG
(PARI) vector(21, n, (n+1)!*n!*binomial(2*n, n)^2/2^(2*n-1) ) \\ G. C. Greubel, Sep 24 2019
(Magma) F:=Factorial; [F(n+2)*F(n+1)*Binomial(2*n+2, n+1)^2/2^(2*n+1): n in [0..20]]; // G. C. Greubel, Sep 24 2019
(Sage) f=factorial; [f(n+2)*f(n+1)*binomial(2*n+2, n+1)^2/2^(2*n+1) for n in (0..20)] # G. C. Greubel, Sep 24 2019
(GAP) F:=Factorial;; List([0..20], n-> F(n+2)*F(n+1)*Binomial(2*n+2, n+1)^2/2^(2*n+1) ); # G. C. Greubel, Sep 24 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Joe Keane (jgk(AT)jgk.org)
EXTENSIONS
More terms added by G. C. Greubel, Sep 24 2019
STATUS
approved