OFFSET
0,2
FORMULA
a(n) = 2(n+1)*3^(n-1), for n>1 (conjectured). - Ralf Stephan, Feb 02 2004
From Colin Barker, Jul 28 2012: (Start)
Conjecture: a(n) = 6*a(n-1)-9*a(n-2), for n>3.
G.f.: (1-9*x^2+18*x^3)/(1-3*x)^2. (End)
CROSSREFS
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(1) corrected and more terms from Sean A. Irvine, Oct 26 2019
STATUS
approved