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

 

Logo

Invitation: celebrating 50 years of OEIS, 250000 sequences, and Sloane's 75th, there will be a conference at DIMACS, Rutgers, Oct 9-10 2014.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A030452 Markov numbers satisfying region 5 (x=5) of the equation x^2 + y^2 + z^2 = 3xyz. 1
1, 2, 13, 29, 194, 433, 2897, 6466, 43261, 96557, 646018, 1441889, 9647009, 21531778, 144059117, 321534781, 2151239746, 4801489937, 32124537073, 71700814274, 479716816349, 1070710724173, 7163627708162, 15988960048321 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Positive values of x (or y) satisfying x^2 - 15xy + y^2 + 25 = 0. - Colin Barker, Feb 11 2014

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..200

Eric Weisstein's World of Mathematics, Markov Number.

Index to sequences with linear recurrences with constant coefficients, signature (0,15,0,-1).

FORMULA

a(n) = 15*a(n-2)-a(n-4).

G.f.: -x*(x-1)*(x^2+3*x+1) / (x^4-15*x^2+1). - Colin Barker, Feb 11 2014

MATHEMATICA

CoefficientList[Series[(1 - x) (x^2 + 3 x + 1)/(x^4 - 15 x^2 + 1), {x, 0, 40}], x] (* Vincenzo Librandi, Feb 12 2014 *)

PROG

(PARI) Vec(-x*(x-1)*(x^2+3*x+1)/(x^4-15*x^2+1) + O(x^100)) \\ Colin Barker, Feb 11 2014

(MAGMA) I:=[1, 2, 13, 29]; [n le 4 select I[n] else 15*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Feb 12 2014

CROSSREFS

Sequence in context: A042917 A174049 A141336 * A132602 A001914 A031392

Adjacent sequences:  A030449 A030450 A030451 * A030453 A030454 A030455

KEYWORD

nonn,easy

AUTHOR

Mark Milhet (mm992395(AT)shellus.com)

EXTENSIONS

More terms from James A. Sellers, May 01 2000

Offset changed to 1 by Colin Barker, Feb 11 2014

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified August 27 15:22 EDT 2014. Contains 246143 sequences.