OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..400
Index entries for linear recurrences with constant coefficients, signature (12,-30,28,-9).
FORMULA
G.f.: (1-4*x+11*x^2+8*x^3)/((1-9*x)*(1-x)^3). - Vincenzo Librandi, Oct 06 2014
a(n) = 12*a(n-1) -30*a(n-2) +28*a(n-3) -9*a(n-4) for n>3. - Vincenzo Librandi, Oct 06 2014
MATHEMATICA
Table[9^n - n^2, {n, 0, 25}] (* or *) CoefficientList[Series[(1 - 4 x + 11 x^2 + 8 x^3)/((1 - 9 x) (1 - x)^3), {x, 0, 30}], x] (* Vincenzo Librandi, Oct 06 2014 *)
PROG
(Magma) [9^n-n^2: n in [0..25]]; // Vincenzo Librandi, Jul 06 2011
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved