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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A117376 Expansion of 1/((1-3x*c(x))(1-x^2*c(x))), c(x) the g.f. of A000108. 1
1, 3, 13, 55, 240, 1057, 4688, 20879, 93250, 417272, 1869725, 8386137, 37640961, 169042436, 759470361, 3413223919, 15343588991, 68988110756, 310233741889, 1395268187372, 6275807975664, 28230370862051, 126996552221811 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Diagonal sums of number triangle A117375.

LINKS

Table of n, a(n) for n=0..22.

FORMULA

a(n)=sum{k=0..floor(n/2), [k<=n-k]*sum{j=0..n-k, (j/(n-k-j))*C(2n-k-j,n-k-j)[k<=j]*3^(j-k)}}

CROSSREFS

Sequence in context: A033887 A291653 A183804 * A264037 A151318 A151212

Adjacent sequences:  A117373 A117374 A117375 * A117377 A117378 A117379

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Mar 10 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 February 21 04:18 EST 2019. Contains 320371 sequences. (Running on oeis4.)