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

 

Logo

"Email this user" was broken Aug 14 to 9am Aug 16. If you sent someone a message in this period, please send it again.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A167373 Expansion of (1+x)*(3*x+1)/(1+x+x^2). 0
1, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1, -2, 3, -1 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Bisection of A138034.

Also row 2n of A137276 or A135929.

REFERENCES

M. Abramowitz and I. A. Stegun, eds., Handbook of Mathematical functions, National Bureau of Standards, Applied Math. Series 55, Tenth Printing, 1972, Chapter 22.

LINKS

Table of n, a(n) for n=0..104.

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

FORMULA

G.f.: (1+x)*(3*x+1)/(1+x+x^2).

a(n) = a(n-3), n>4.

a(n) = - a(n-1) - a(n-2) for n>2.

a(n) = 4*sin(2*n*Pi/3)/sqrt(3)-2*cos(2*n*Pi/3) for n>0 with a(0)=1. - Wesley Ivan Hurt, Jun 12 2016

MATHEMATICA

CoefficientList[Series[(1 + x)*(3*x + 1)/(1 + x + x^2), {x, 0, 50}], x] (* G. C. Greubel, Jun 12 2016 *)

CROSSREFS

Cf. A135929, A138034, A137276.

Sequence in context: A195588 A153510 A288537 * A079722 A079723 A080511

Adjacent sequences:  A167370 A167371 A167372 * A167374 A167375 A167376

KEYWORD

sign,easy

AUTHOR

Jamel Ghanouchi, Nov 02 2009

EXTENSIONS

Edited by R. J. Mathar, Nov 03 2009

Further edited and extended by Simon Plouffe, Nov 23 2009

Recomputed by N. J. A. Sloane, Dec 20 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 20 17:26 EDT 2017. Contains 290837 sequences.