login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A100133 a(n) = Sum_{k=0..floor(n/4)} C(n-2k,2k) * 3^k * 2^(n-4k). 4
1, 2, 4, 8, 19, 50, 136, 368, 985, 2618, 6940, 18392, 48763, 129338, 343120, 910304, 2415025, 6406898, 16996852, 45090728, 119620579, 317340098, 841868632, 2233386320, 5924932489, 15718204970, 41698695820, 110622122360 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Binomial transform of 1,1,1,1,4,4,10,10,28,28,76,... (g.f. (1-x)(1+x)^2/(1-2x^2-2x^4)).

LINKS

Seiichi Manyama, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4,-4,0,3)

FORMULA

G.f.: (1-2x)/((1-2x)^2-3x^4).

a(n) = 4*a(n-1) - 4*a(n-2) + 3*a(n-3).

PROG

(PARI) a(n) = sum(k=0, n\4, binomial(n-2*k, 2*k) * 3^k * 2^(n-4*k)); \\ Michel Marcus, Oct 09 2021

CROSSREFS

Cf. A100131, A100132.

Sequence in context: A005703 A172383 A003081 * A099598 A269023 A173310

Adjacent sequences:  A100130 A100131 A100132 * A100134 A100135 A100136

KEYWORD

easy,nonn

AUTHOR

Paul Barry, Nov 06 2004

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 October 23 21:27 EDT 2021. Contains 348217 sequences. (Running on oeis4.)