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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A015561 Expansion of x/(1 - 7*x - 4*x^2). 3
0, 1, 7, 53, 399, 3005, 22631, 170437, 1283583, 9666829, 72802135, 548282261, 4129184367, 31097419613, 234198674759, 1763780401765, 13283257511391, 100037924186797, 753398499353143, 5673941192219189, 42731182342946895 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (7,4).

FORMULA

a(n) = 7*a(n-1) + 4*a(n-2).

a(n) = -(1/65)*sqrt(65)*(7/2 - (1/2)*sqrt(65))^n + (1/65)*sqrt(65)*(7/2 + (1/2)*sqrt(65))^n, with n >= 0. - Paolo P. Lava, Jun 25 2008

MATHEMATICA

Join[{a=0, b=1}, Table[c=7*b+4*a; a=b; b=c, {n, 100}]] (* Vladimir Joseph Stephan Orlovsky, Jan 17 2011 *)

LinearRecurrence[{7, 4}, {0, 1}, 30] (* Vincenzo Librandi, Nov 14 2012 *)

PROG

(Sage) [lucas_number1(n, 7, -4) for n in xrange(0, 21)] # Zerinvary Lajos, Apr 24 2009

(MAGMA) [n le 2 select n-1 else 7*Self(n-1) + 4*Self(n-2): n in [1..30]]; // Vincenzo Librandi, Nov 14 2012

(PARI) x='x+O('x^30); concat([0], Vec(x/(1-7*x-4*x^2))) \\ G. C. Greubel, Dec 30 2017

CROSSREFS

Sequence in context: A223712 A065542 A279269 * A133588 A163306 A081338

Adjacent sequences:  A015558 A015559 A015560 * A015562 A015563 A015564

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

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 21 14:52 EDT 2019. Contains 328301 sequences. (Running on oeis4.)