This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A159331 Transform of the finite sequence (1, 0, -1, 0, 1, 0, -1) by the T_{1,1} transform (see link). 2
 2, 4, 9, 23, 55, 126, 293, 680, 1581, 3676, 8546, 19867, 46185, 107367, 249598, 580245, 1348906, 3135826, 7289911, 16946987, 39396965, 91586832, 212913553, 494963960, 1150651606, 2674940451, 6218482101, 14456217007, 33606627270 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS G. C. Greubel, Table of n, a(n) for n = 0..1000 R. Choulet, Curtz-like transformation. Index entries for linear recurrences with constant coefficients, signature (3,-2,1). FORMULA O.g.f.: f(z) = ((1-z)^2/(1-3*z+2*z^2-z^3))*(1-z^2+z^4+z^6) + (z/(1-3*z+2*z^2-z^3)) + ((1-z+z^2)/(1-3*z+2*z^2-z^3)). a(n) = 3*a(n-1) - 2*a(n-2) + a(n-3) for n >= 9, with a(0)=2, a(1)=4, a(2)=9, a(3)=23, a(4)=55, a(5)=126, a(6)=293, a(7)=680, a(8)=1581. MATHEMATICA Join[{2, 4, 9, 23, 55, 126}, LinearRecurrence[{3, -2, 1}, {293, 680, 1581}, 45]] (* G. C. Greubel, Jun 26 2018 *) PROG (PARI) z='z+O('z^30); Vec(((1-z)^2/(1-3*z+2*z^2-z^3))*(1-z^2+z^4+z^6) + (z/(1-3*z+2*z^2-z^3)) + ((1-z+z^2)/(1-3*z+2*z^2-z^3))) \\ G. C. Greubel, Jun 26 2018 (MAGMA) I:=[293, 680, 1581]; [2, 4, 9, 23, 55, 126] cat [n le 3 select I[n] else 3*Self(n-1) - 2*Self(n-2) + Self(n-3): n in [1..30]]; // G. C. Greubel, Jun 26 2018 CROSSREFS Cf. A159328, A159329, A159330. Sequence in context: A159329 A159334 A159330 * A135346 A174283 A268172 Adjacent sequences:  A159328 A159329 A159330 * A159332 A159333 A159334 KEYWORD easy,nonn AUTHOR Richard Choulet, Apr 10 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 November 16 05:13 EST 2018. Contains 317257 sequences. (Running on oeis4.)