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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A122908 A central binomial scaling of the Riordan array (1+x,x) (A097806). 0
1, 1, 1, 0, 1, 2, 0, 0, 2, 3, 0, 0, 0, 3, 6, 0, 0, 0, 0, 6, 10, 0, 0, 0, 0, 0, 10, 20, 0, 0, 0, 0, 0, 0, 20, 35, 0, 0, 0, 0, 0, 0, 0, 35, 70, 0, 0, 0, 0, 0, 0, 0, 0, 70, 126, 0, 0, 0, 0, 0, 0, 0, 0, 0, 126, 252 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

Row sums are A050168. Diagonal sums are A001045 doubled. Row sums of inverse are 1/C(2n,n) aerated. Applications to other sequences are obvious.

LINKS

Table of n, a(n) for n=0..65.

FORMULA

Number triangle T(n,k)=C(k,floor(k/2))*sum{j=0..n, (-1)^(n-j)C(n,j)C(j+1,k+1)}

EXAMPLE

Triangle begins

.1,

.1, 1,

.0, 1, 2,

.0, 0, 2, 3,

.0, 0, 0, 3, 6,

.0, 0, 0, 0, 6, 10,

.0, 0, 0, 0, 0, 10, 20,

.0, 0, 0, 0, 0, 0, 20, 35,

.0, 0, 0, 0, 0, 0, 0, 35, 70,

.0, 0, 0, 0, 0, 0, 0, 0, 70, 126,

.0, 0, 0, 0, 0, 0, 0, 0, 0, 126, 252

CROSSREFS

Sequence in context: A282133 A153869 A128541 * A296441 A091008 A111006

Adjacent sequences:  A122905 A122906 A122907 * A122909 A122910 A122911

KEYWORD

easy,nonn,tabl

AUTHOR

Paul Barry, Sep 18 2006

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
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 12 19:41 EST 2019. Contains 329078 sequences. (Running on oeis4.)