This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A180400 Coefficients of Maclaurin series for (1-9x-9x^2)^(-1/3). 2
 1, 3, 21, 162, 1341, 11529, 101619, 911466, 8281737, 76002381, 703017549, 6544803564, 61254970686, 575885086182, 5434948357146, 51462813578148, 488705091057981, 4652700300002475, 44395945025504625, 424479488258350350 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..200 FORMULA G.f.: (1-9x-9x^2)^(-1/3). Recurrence: n*a(n) = 3*(3*n-2)*a(n-1) + 3*(3*n-4)*a(n-2). - Vaclav Kotesovec, Oct 20 2012 a(n) ~ sqrt(3)*Gamma(2/3)/(2^(2/3)*(13-3*sqrt(13))^(1/3)*Pi) * ((9+3*sqrt(13))/2)^n/(n^(2/3)). - Vaclav Kotesovec, Oct 20 2012 EXAMPLE The Maclaurin series begins with 1 + 3x + 21x^2. MATHEMATICA CoefficientList[Series[Power[1-9x-9x^2, (-3)^-1], {x, 0, 20}], x] (* Harvey P. Dale, Mar 11 2012 *) CROSSREFS Cf. A180399. Sequence in context: A074570 A136781 A225439 * A166696 A058194 A179815 Adjacent sequences:  A180397 A180398 A180399 * A180401 A180402 A180403 KEYWORD nonn,easy AUTHOR Clark Kimberling, Sep 01 2010, Sep 02 2010 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.

Last modified December 12 15:11 EST 2019. Contains 329960 sequences. (Running on oeis4.)