login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A084778 a(n) = sum of absolute-valued coefficients of (1+2x-3x^2)^n. 2
1, 6, 28, 128, 660, 3016, 13108, 64112, 304068, 1332992, 6514356, 29341384, 131904528, 623547112, 2990903464, 13436119424, 61647598484, 284398511848, 1302463169256, 6195158123688, 28653898573420, 130138400720504 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..21.

PROG

(PARI) for(n=0, 40, S=sum(k=0, 2*n, abs(polcoeff((1+2*x-3*x^2)^n, k, x))); print1(S", "))

CROSSREFS

Sequence in context: A351053 A171859 A338584 * A287807 A155588 A208439

Adjacent sequences: A084775 A084776 A084777 * A084779 A084780 A084781

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 14 2003

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 8 14:48 EST 2023. Contains 360146 sequences. (Running on oeis4.)