OFFSET
0,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (6,-9).
FORMULA
a(0)=1, a(1)=4, a(2)=20, a(n) = 6*a(n-1) - 9*a(n-2) for n>2.
a(n) = 4*A081038(n-1) for n>0.
a(n) = Sum_{k=0..n} A167666(n,k)*3^k.
a(n) = 3^(n - 2)*(8*n + 4) for n>0. - Colin Barker, Jan 21 2017
MATHEMATICA
CoefficientList[Series[(1-2x+5*x^2)/(1-3x)^2, {x, 0, 40}], x] (* or *) Join[{1}, LinearRecurrence[{6, -9}, {4, 20}, 40]] (* Harvey P. Dale, Oct 20 2011 *)
PROG
(PARI) Vec((1-2*x+5*x^2) / (1-3*x)^2 + O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Philippe Deléham, Nov 09 2009
EXTENSIONS
Corrected and extended by Harvey P. Dale, Oct 20 2011
PARI code corrected by Colin Barker, Jan 21 2017
STATUS
approved