OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000 (corrected by Ray Chandler, Jan 19 2019)
Index entries for linear recurrences with constant coefficients, signature (36,-486,2916,-6561).
FORMULA
a(1)=18, a(2)=810, a(3)=21870, a(4)=446148, a(n)=36*a(n-1)- 486*a(n-2)+ 2916*a(n-3)-6561*a(n-4). - Harvey P. Dale, Jun 16 2011
G.f.: 18*x*(1+9*x+81*x^2)/(1-9*x)^4. - Harvey P. Dale, Jun 16 2011
MATHEMATICA
Table[(n^3+n)9^n, {n, 20}] (* or *) LinearRecurrence[{36, -486, 2916, -6561}, {18, 810, 21870, 446148}, 20] (* Harvey P. Dale, Jun 16 2011 *)
PROG
(Magma) [(n^3 + n) * 9^n: n in [1..20]]; // Vincenzo Librandi, Feb 22 2012
(PARI) A128074(n)=(n^3+n)*9^n \\ M. F. Hasler, Oct 06 2014
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, May 02 2007
EXTENSIONS
Extended to a(0)=0 by M. F. Hasler, Oct 06 2014
STATUS
approved