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

 

Logo

Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing.
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A077912 Expansion of 1/(1+x^2-2*x^3). 2
1, 0, -1, 2, 1, -4, 3, 6, -11, 0, 23, -22, -23, 68, -21, -114, 157, 72, -385, 242, 529, -1012, -45, 2070, -1979, -2160, 6119, -1798, -10439, 14036, 6843, -34914, 21229, 48600, -91057, -6142, 188257, -175972, -200541, 552486, -151403, -953568, 1256375, 650762, -3163511, 1861988, 4465035 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Equally, expansion of (1-x)^(-1)/(1+x+2*x^2).

LINKS

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

Index entries for linear recurrences with constant coefficients, signature (0, -1, 2).

FORMULA

a(0)=1, a(1)=0, a(2)=-1, a(n) = -a(n-2)+2*a(n-3). - Harvey P. Dale, Dec 10 2012

a(n) = (-1)^n * A077963(n). - G. C. Greubel, Jun 23 2019

MATHEMATICA

CoefficientList[Series[1/(1+x^2-2*x^3), {x, 0, 50}], x] (* or *) LinearRecurrence[{0, -1, 2}, {1, 0, -1}, 50] (* Harvey P. Dale, Dec 10 2012 *)

PROG

(PARI) my(x='x+O('x^50)); Vec(1/(1+x^2-2*x^3)) \\ G. C. Greubel, Jun 23 2019

(MAGMA) R<x>:=PowerSeriesRing(Integers(), 50); Coefficients(R!( 1/(1+x^2-2*x^3) )); // G. C. Greubel, Jun 23 2019

(Sage) (1/(1+x^2-2*x^3)).series(x, 50).coefficients(x, sparse=False) # G. C. Greubel, Jun 23 2019

(GAP) a:=[1, 0, -1];; for n in [4..50] do a[n]:=-a[n-2]+2*a[n-3]; od; a; # G. C. Greubel, Jun 23 2019

CROSSREFS

Cf. A077963.

Sequence in context: A105361 A125154 A281853 * A077963 A114861 A086512

Adjacent sequences:  A077909 A077910 A077911 * A077913 A077914 A077915

KEYWORD

sign,easy

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 December 5 13:26 EST 2019. Contains 329751 sequences. (Running on oeis4.)