This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A168494 Sequence with Hankel transform equal to 3^floor(n^2/3). 2
 1, 1, 2, 7, 32, 160, 830, 4405, 23798, 130498, 724748, 4069258, 23064608, 131809108, 758696492, 4394825647, 25600773272, 149877922228, 881394158558, 5204245242208, 30841413359186, 183381577399006, 1093695670905206 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Hankel transform is A168495. LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..300 FORMULA G.f.: 1/(1-x/(1-x/(1-3x/(1-x/(1-x/(1-3x/(1-x/(1-x/(1-3x/(1-.... (continued fraction); G.f.: 1/(1-x-x^2/(1-4x-3x^2/(1-2x-3x^2/(1-4x-x^2/(1-4x-3x^2/(1-2x-3x^2/(1-4x-x^2/(1-... (continued fraction), with sequences (1,3,3,1,3,3,1,3,3,1,...) and (1,4,2,4,4,2,4,4,2,4,4,...). G.f.: (1+x-sqrt(1-10x+25x^2-12x^3))/(6x(1-x)). a(n) = Sum_{k=0..n} A091866(n,k)*3^(n-k). - Philippe Deléham, Nov 27 2009 Conjecture: (n+1)*a(n) +(4-11*n)*a(n-2) +5*(7*n-11)*a(n-2) +(92-37*n) * a(n-3) +6*(2*n-7)*a(n-4) = 0. - R. J. Mathar, Sep 30 2012 a(n) ~ sqrt(33-sqrt(33))*((7+sqrt(33))/2)^n/(12*sqrt(Pi)*n^(3/2)). - Vaclav Kotesovec, Oct 24 2012 MATHEMATICA CoefficientList[Series[(1+x-Sqrt[1-10*x+25*x^2-12*x^3])/(6*x*(1-x)), {x, 0, 20}], x] (* Vaclav Kotesovec, Oct 24 2012 *) CROSSREFS Cf. A000108, A091866, A109033. - Philippe Deléham, Nov 27 2009 Sequence in context: A015655 A047850 A201373 * A181376 A183951 A226994 Adjacent sequences:  A168491 A168492 A168493 * A168495 A168496 A168497 KEYWORD easy,nonn AUTHOR Paul Barry, Nov 27 2009 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 15 22:21 EDT 2018. Contains 316252 sequences. (Running on oeis4.)