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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A032127 "BIK" (reversible, indistinct, unlabeled) transform of 1,3,5,7... 1
1, 4, 9, 25, 63, 183, 513, 1521, 4455, 13311, 39609, 118665, 355023, 1064583, 3190833, 9571041, 28704375, 86108751, 258300009, 774886905, 2324581983, 6973706583, 20920883553, 62762532561, 188286889095, 564860312991, 1694578813209, 5083735376745, 15251199752943 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

C. G. Bower, Transforms (2)

Index entries for linear recurrences with constant coefficients, signature (3,3,-9).

FORMULA

For n>2, a(n) = (1/9)*((8-(-1)^n)*3^floor(n/2) + 2*3^n). - Ralf Stephan, May 11 2004

G.f.: -x*(3*x^4+5*x^3+6*x^2-x-1) / ((3*x-1)*(3*x^2-1)). - Colin Barker, Dec 15 2012

MATHEMATICA

CoefficientList[Series[-(3 x^4 + 5 x^3 + 6 x^2 - x - 1)/((3 x - 1) (3 x^2 - 1)), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 19 2013 *)

LinearRecurrence[{3, 3, -9}, {1, 4, 9, 25, 63}, 30] (* Harvey P. Dale, Feb 20 2016 *)

PROG

(MAGMA) [1, 4] cat [(1/9)*((8-(-1)^n)*3^Floor(n/2) + 2*3^n): n in [3..30]]; // Vincenzo Librandi, Oct 19 2013

CROSSREFS

Sequence in context: A030481 A160190 A226917 * A181357 A244558 A175627

Adjacent sequences:  A032124 A032125 A032126 * A032128 A032129 A032130

KEYWORD

nonn,easy

AUTHOR

Christian G. Bower

EXTENSIONS

More terms from Vincenzo Librandi, Oct 19 2013

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 October 17 16:34 EDT 2018. Contains 316285 sequences. (Running on oeis4.)