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 A059738 Binomial transform of A054341 and inverse binomial transform of A049027. 9
 1, 3, 10, 34, 117, 405, 1407, 4899, 17083, 59629, 208284, 727900, 2544751, 8898873, 31125138, 108881166, 380928795, 1332824049, 4663705782, 16319702046, 57109857519, 199859075307, 699435489795, 2447823832671, 8566818534141, 29982268505595, 104933418068332 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS First column of the Riordan array ((1-2x)/(1+x+x^2),x/(1+x+x^2))^(-1). [Paul Barry, Nov 06 2008] Apparently the Motzkin transform of A125176, supposed A125176 is interpreted with offset 0. [R. J. Mathar, Dec 11 2008] a(n) is the number of Motzkin paths of length n in which the (1,0)-steps at level 0 come in 3 colors. Example: a(3)=34 because, denoting  U=(1,1), H=(1,0), and D=(1,-1), we have 3^3 = 27 paths of shape HHH, 3 paths of shape HUD, 3 paths of shape UDH, and 1 path of shape UHD. - Emeric Deutsch, May 02 2011 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..1000 Aoife Hennessy, A Study of Riordan Arrays with Applications to Continued Fractions, Orthogonal Polynomials and Lattice Paths, Ph. D. Thesis, Waterford Institute of Technology, Oct. 2011. J. W. Layman, The Hankel Transform and Some of its Properties, J. Integer Sequences, 4 (2001), #01.1.5. FORMULA a(n) = Sum[k=0..n, 2^(n-k)*A026300(n, k) ], where A026300 is the Motzkin triangle. - Ralf Stephan, Jan 25 2005 [Corrected by Philippe Deléham, Nov 29 2009] a(n)= A126954(n,0). [Philippe Deléham, Nov 24 2009] G.f.: 2/(1-5*x+sqrt(1-2*x-3*x^2)). - Emeric Deutsch, May 02 2011 Recurrence: 2*(n+1)*a(n) = (11*n+5)*a(n-1) - (8*n+5)*a(n-2) - 21*(n-2)*a(n-3). - Vaclav Kotesovec, Oct 11 2012 a(n) ~ 3*7^n/2^(n+2). - Vaclav Kotesovec, Oct 11 2012 MATHEMATICA Table[SeriesCoefficient[2/(1-5*x+Sqrt[1-2*x-3*x^2]), {x, 0, n}], {n, 0, 20}] PROG (PARI) x='x+O('x^66); Vec(2/(1-5*x+sqrt(1-2*x-3*x^2))) \\ Joerg Arndt, May 06 2013 CROSSREFS Sequence in context: A007052 A048580 A289612 * A094832 A217778 A071725 Adjacent sequences:  A059735 A059736 A059737 * A059739 A059740 A059741 KEYWORD nonn AUTHOR John W. Layman, Feb 09 2001 EXTENSIONS More terms from Vincenzo Librandi, May 06 2013 STATUS approved

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Last modified October 17 05:23 EDT 2018. Contains 316275 sequences. (Running on oeis4.)