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

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A082590 Expansion of 1/((1-2*x)*sqrt(1-4*x)). 15
1, 4, 14, 48, 166, 584, 2092, 7616, 28102, 104824, 394404, 1494240, 5692636, 21785872, 83688344, 322494208, 1246068806, 4825743832, 18726622964, 72798509728, 283443548276, 1105144970992, 4314388905704, 16862208539008 (list; graph; refs; listen; history; internal format)
OFFSET

0,2

COMMENTS

A0344309(n) = (n!/2^n)*a(n). A076729(n) = n!*a(n).

Row sums of A068555 and A112336. - Paul Barry (pbarry(AT)wit.ie), Sep 04 2005

Hankel transform is 2^n*(-1)^C(n+1,2) (A120617). [From Paul Barry (pbarry(AT)wit.ie), Apr 26 2009]

FORMULA

a(n) = 2^n*JacobiP(n, 1/2, -1-n, 3).

a(n)=sum{k=0..n+1, binomial(2n+2, k)*sin((n-k+1)*pi/2} - Paul Barry (pbarry(AT)wit.ie), Nov 02 2004

a(n)=sum{k=0..n, 2^(n-k)*binomial(2k, k)}; a(n)=sum{k=0..n, (2k)!(2(n-k))!/(n!k!(n-k)!)}; - Paul Barry (pbarry(AT)wit.ie), Sep 04 2005

a(n)=sum{k=0..n, C(2n,n)C(n,k)/C(2n,2k)} - Paul Barry (pbarry(AT)wit.ie), Mar 18 2007

G.f.: 1/(1-4x+2x^2/(1+x^2/(1-4x+x^2/(1+x^2/(1-4x+x^2/(1+... (continued fraction). [From Paul Barry (pbarry(AT)wit.ie), Apr 26 2009]

CROSSREFS

Sequence in context: A071749 A071753 A071757 * A085280 A007851 A014325

Adjacent sequences:  A082587 A082588 A082589 * A082591 A082592 A082593

KEYWORD

nonn

AUTHOR

Vladeta Jovovic (vladeta(AT)eunet.rs), May 13 2003

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

Content is available under The OEIS End-User License Agreement .

Last modified February 16 09:00 EST 2012. Contains 205904 sequences.