OFFSET
0,2
COMMENTS
The e.g.f. given below is Sum_{m=0..1} (A075513(3,m)*exp(9*(m+1)*x)).
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..796
Index entries for linear recurrences with constant coefficients, signature (27,-162).
FORMULA
a(n) = -9^n + 2*18^n.
G.f.: 1/((1-9*x)*(1-18*x)).
E.g.f.: (d^2/dx^2)(((exp(9*x)-1)/9)^2)/2! = -exp(9*x) + 2*exp(18*x).
a(0)=1, a(1)=27, a(n) = 27*a(n-1) - 162*a(n-2). - Harvey P. Dale, Dec 01 2015
MATHEMATICA
CoefficientList[Series[1/((1-9x)(1-18x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{27, -162}, {1, 27}, 30] (* Harvey P. Dale, Dec 01 2015 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Wolfdieter Lang, Oct 02 2002
STATUS
approved