OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (9,-27,27).
FORMULA
G.f.: 3*x*(1 + 3*x)/(1 - 3*x)^3. - Vincenzo Librandi, Feb 07 2013
a(n) = 9*a(n-1) - 27*a(n-2) + 27*a(n-3). - Vincenzo Librandi, Feb 07 2013
a(n) = 3*A069996(n) for n>0. - Bruno Berselli, Feb 07 2013
E.g.f.: (9*x^2 + 3*x)*exp(3*x). - G. C. Greubel, May 04 2018
MATHEMATICA
LinearRecurrence[{9, -27, 27}, {0, 3, 36}, 25] (* or *) CoefficientList[ Series[3*x(1 + 3*x)/(1 - 3*x)^3, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 07 2013 *)
PROG
(Magma) [n^2*3^n: n in [0..30]]; // Vincenzo Librandi, Feb 07 2013
(PARI) for(n=0, 30, print1(n^2*3^n, ", ")) \\ G. C. Greubel, May 04 2018
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Apr 07 2007
STATUS
approved