OFFSET
0,2
LINKS
Index entries for linear recurrences with constant coefficients, signature (8,-21,18).
FORMULA
a(n)=2^n+2n*3^(n-1); a(n)=sum{k=0..n, C(n, k)(1+k*2^k) }.
O.g.f.: (1-4x+5x^2)/[(1-2x)(-1+3x)^2]. - R. J. Mathar, Apr 02 2008
a(0)=1, a(1)=4, a(2)=16, a(n)=8*a(n-1)-21*a(n-2)+18*a(n-3). - Harvey P. Dale, Mar 31 2015
MATHEMATICA
LinearRecurrence[{8, -21, 18}, {1, 4, 16}, 30] (* Harvey P. Dale, Mar 31 2015 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Jun 12 2003
STATUS
approved