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

 

Logo

The submissions stack has been unacceptably high for several months now. Please voluntarily restrict your submissions and please help with the editing. (We don't want to have to impose further limits.)

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A128593 Column 1 of triangle A128592; a(n) = coefficient of q^(n+2) in the q-analog of the odd double factorials (2n+3)!! for n>=0. 3
1, 3, 12, 45, 170, 644, 2451, 9365, 35908, 138104, 532589, 2058782, 7975216, 30951921, 120326060, 468473348, 1826415556, 7129330988, 27860219331, 108984557708, 426730087879, 1672310507262, 6558840830680, 25742937514814 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..23.

FORMULA

a(n) = [q^(n+2)] Product_{j=1..n+2} (1-q^(2j-1))/(1-q) for n>=0.

PROG

(PARI) {a(n)=polcoeff(prod(j=1, n+2, (1-q^(2*j-1))/(1-q)), n+2, q)}

CROSSREFS

Cf. A128592; A128080; A001147 ((2n-1)!!); A128594 (column 2), A128595 (row sums).

Sequence in context: A064017 A005320 A062561 * A085481 A030195 A114515

Adjacent sequences:  A128590 A128591 A128592 * A128594 A128595 A128596

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Mar 12 2007

STATUS

approved

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

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

Last modified August 28 03:16 EDT 2015. Contains 261112 sequences.