login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A065140 a(n) = 2^n*(2*n)!. 4
1, 4, 96, 5760, 645120, 116121600, 30656102400, 11158821273600, 5356234211328000, 3278015337332736000, 2491291656372879360000, 2301953490488540528640000, 2541356653499348743618560000 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Harry J. Smith, Table of n, a(n) for n=0..100

FORMULA

Hypergeometric generating function, in Maple notation: 1/sqrt(1-8*x), i.e. a(0)=1, a(n)=round(evalf(subs(x=0, n!*diff(1/(sqrt(1-8*x)), x$n)))), n=1, 2... Integral representation as n-th moment of a positive function on a positive half-axis: a(n)=int(x^n*exp(-sqrt(x/2))/(2*sqrt(2*x)), x=0..infinity), n=0, 1....

G.f.: G(0)/2, where G(k)= 1 + 1/(1 - 4*x*(k+1)*(2*k+1)/(4*x*(k+1)*(2*k+1) + 1/G(k+1))); (continued fraction). - Sergei N. Gladkovskii, Jun 07 2013

MATHEMATICA

Table[2^n (2n)!, {n, 0, 15}] (* Harvey P. Dale, Nov 28 2011 *)

PROG

(PARI) { for (n=0, 100, write("b065140.txt", n, " ", 2^n*(2*n)!) ) } \\ Harry J. Smith, Oct 11 2009

CROSSREFS

Sequence in context: A077155 A013042 A190196 * A007106 A111637 A027872

Adjacent sequences:  A065137 A065138 A065139 * A065141 A065142 A065143

KEYWORD

nonn

AUTHOR

Karol A. Penson, Oct 16 2001

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy .

Last modified November 18 05:25 EST 2017. Contains 294853 sequences.