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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A077993 Expansion of 1/(1+2*x+2*x^2+2*x^3). 1
1, -2, 2, -2, 4, -8, 12, -16, 24, -40, 64, -96, 144, -224, 352, -544, 832, -1280, 1984, -3072, 4736, -7296, 11264, -17408, 26880, -41472, 64000, -98816, 152576, -235520, 363520, -561152, 866304, -1337344, 2064384, -3186688, 4919296, -7593984, 11722752, -18096128, 27934720, -43122688 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (-2,-2,-2).

FORMULA

a(n) = (-1)^n * A077943(n). - R. J. Mathar, Aug 04 2008

MATHEMATICA

LinearRecurrence[{-2, -2, -2}, {1, -2, 2}, 50] (* or *) CoefficientList[ Series[1/(1+2*x+2*x^2+2*x^3), {x, 0, 50}], x] (* G. C. Greubel, Jun 27 2019 *)

PROG

(PARI) my(x='x+O('x^50)); Vec(1/(1+2*x+2*x^2+2*x^3)) \\ G. C. Greubel, Jun 27 2019

(MAGMA) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1+2*x+2*x^2+2*x^3) )); // G. C. Greubel, Jun 27 2019

(Sage) (1/(1+2*x+2*x^2+2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 27 2019

(GAP) a:=[1, -2, 2];; for n in [4..50] do a[n]:=-2*(a[n-1]+a[n-2]+a[n-3]); od; a; # G. C. Greubel, Jun 27 2019

CROSSREFS

Cf. A077943.

Sequence in context: A306337 A326022 A077943 * A302613 A295680 A099768

Adjacent sequences:  A077990 A077991 A077992 * A077994 A077995 A077996

KEYWORD

sign

AUTHOR

N. J. A. Sloane, Nov 17 2002

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 14 09:25 EDT 2019. Contains 327995 sequences. (Running on oeis4.)