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!)
A084777 a(n) = sum of absolute-valued coefficients of (1+2x-2x^2)^n. 2
1, 5, 17, 73, 273, 881, 3785, 13081, 48737, 184321, 632193, 2526305, 8854081, 32077921, 124093025, 428178641, 1638563969, 5878561921, 21469361537, 82252171393, 286863949025, 1061000856417, 3998983314849, 14361380710817 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

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

PROG

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

CROSSREFS

Sequence in context: A354040 A187823 A297625 * A149717 A149718 A149719

Adjacent sequences: A084774 A084775 A084776 * A084778 A084779 A084780

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 January 29 06:03 EST 2023. Contains 359915 sequences. (Running on oeis4.)