The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A003955 a(n) = (2*n + 4) * (1*3*5*...*(2*n+1))^2. 1
 4, 54, 1800, 110250, 10716300, 1512784350, 292183491600, 73958946311250, 23749039426612500, 9430743556307823750, 4537044990907363935000, 2600104866872495148416250, 1750070583471871734510937500, 1366930130733208386919792968750, 1226227455943070136959515612500000 (list; graph; refs; listen; history; text; internal format)
 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 Cf. A001818. Sequence in context: A225823 A265004 A284747 * A182264 A355128 A355126 Adjacent sequences: A003952 A003953 A003954 * A003956 A003957 A003958 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 27 20:09 EDT 2023. Contains 362985 sequences. (Running on oeis4.)