The OEIS is supported by the many generous donors to the OEIS Foundation.

 Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 60th year, we have over 367,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”). Other ways to Give
 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A016172 Expansion of 1/((1-6x)(1-9x)). 1
 1, 15, 171, 1755, 17091, 161595, 1501011, 13789035, 125780931, 1142106075, 10339420851, 93417584715, 842935044771, 7599476096955, 68473649036691, 616733026314795, 5553418346740611, 49997691780110235 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..17. Index entries for linear recurrences with constant coefficients, signature (15,-54). FORMULA a(n) = (9^(n+1)-6^(n+1))/3. - Lambert Klasen (lambert.klasen(AT)gmx.net), Feb 05 2005 a(0)=1, a(n) = 9*a(n-1) + 6^n. - Vincenzo Librandi, Feb 09 2011 a(0)=1, a(1)=15, a(n) = 15*a(n-1) - 54*a(n-2). - Vincenzo Librandi, Feb 09 2011 MATHEMATICA Join[{a=1, b=15}, Table[c=15*b-54*a; a=b; b=c, {n, 60}]] (* Vladimir Joseph Stephan Orlovsky, Feb 01 2011 *) CoefficientList[Series[1/((1-6x)(1-9x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{15, -54}, {1, 15}, 30] (* Harvey P. Dale, Oct 07 2015 *) PROG (PARI) Vec(1/((1-6*x)*(1-9*x))+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012 CROSSREFS Sequence in context: A339770 A240276 A206600 * A016225 A058687 A206594 Adjacent sequences: A016169 A016170 A016171 * A016173 A016174 A016175 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 | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 7 18:28 EST 2023. Contains 367660 sequences. (Running on oeis4.)