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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A016321 Expansion of 1/((1-2x)(1-9x)(1-10x)). 6
1, 21, 313, 4065, 49081, 566721, 6350473, 69654225, 751887961, 8016991521, 84652923433, 886876310385, 9231886792441, 95586981129921, 985282830165193, 10117545471478545, 103557909243290521, 1057021183189581921 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..900

Index entries for linear recurrences with constant coefficients, signature (21,-128,180).

FORMULA

From Zerinvary Lajos, Jun 05 2009 [corrected by R. J. Mathar, Mar 14 2011]: (Start)

a(n) = 2^(n-1)/7 - 9^(n+2)/7 + 25*10^n/2.

a(n) = A016134(n+1) - A016133(n+1). (End)

From Vincenzo Librandi, Oct 09 2011: (Start)

a(n) = (175*10^n + 2^n - 2*9^(n+2))/14.

a(n) = 19*a(n-1) - 90*a(n-2) + 2^n.

a(n) = 21*a(n-1) - 128*a(n-2) + 180*a(n-3), n >= 3. (End)

MATHEMATICA

CoefficientList[Series[1/((1-2x)(1-9x)(1-10x)), {x, 0, 20}], x] (* or *) LinearRecurrence[{21, -128, 180}, {1, 21, 313}, 20] (* Harvey P. Dale, Aug 18 2014 *)

PROG

(Sage) [(10^n - 2^n)/8-(9^n - 2^n)/7 for n in xrange(2, 20)] # Zerinvary Lajos, Jun 05 2009

(MAGMA) [(175*10^n +2^n-2*9^(n+2))/14 : n in [0..20]]; // Vincenzo Librandi, Oct 09 2011

(PARI) a(n) = (175*10^n+2^n-162*9^n)/14 \\ Charles R Greathouse IV, Sep 23 2012

CROSSREFS

Cf. A016133, A016134.

Sequence in context: A281254 A157088 A226990 * A019041 A021214 A016318

Adjacent sequences:  A016318 A016319 A016320 * A016322 A016323 A016324

KEYWORD

nonn,easy

AUTHOR

N. J. A. Sloane

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 April 21 04:56 EDT 2019. Contains 322310 sequences. (Running on oeis4.)