A066374 (3*n+4)*2^(n-3)-(2*n-1).

2, 8, 25, 67, 165, 387, 881, 1967, 4333, 9451, 20457, 44007, 94181, 200675, 425953, 901087, 1900509, 3997659, 8388569, 17563607, 36700117, 76546003, 159383505, 331349967, 687865805, 1426063307, 2952789961, 6106906567

Offset

2,1

Links

Harry J. Smith, Table of n, a(n) for n = 2..200

M. Azaola and F. Santos, The number of triangulations of the cyclic polytope C(n,n-4), Discrete Comput. Geom., 27 (2002), 29-48.

Index entries for linear recurrences with constant coefficients, signature (6, -13, 12, -4).

Formula

G.f.: x^2*(2-4*x+3*x^2-3*x^3)/((1-x)^2*(1-2*x)^2). [Colin Barker, Apr 20 2012]

a(2)=2, a(3)=8, a(4)=25, a(5)=67, a(n)=6*a(n-1)-13*a(n-2)+12*a(n-3)- 4*a(n-4). - Harvey P. Dale, Oct 23 2013

Mathematica

Table[(3n+4)2^(n-3)-(2n-1), {n, 2, 30}] (* or *) LinearRecurrence[ {6, -13, 12, -4}, {2, 8, 25, 67}, 30] (* Harvey P. Dale, Oct 23 2013 *)

Prog

(PARI) { for (n=2, 200, write("b066374.txt", n, " ", (3*n + 4)*2^(n -3 ) - (2*n - 1)) ) } [Harry J. Smith, Feb 11 2010]

Crossrefs

Sequence in context: A198181 A066455 A370637 * A193048 A301819 A119854

Adjacent sequences: A066371 A066372 A066373 * A066375 A066376 A066377

Keyword

nonn,easy

Author

N. J. A. Sloane, Jan 04 2002

Status

approved