OFFSET
0,2
LINKS
Guo-Niu Han, Enumeration of Standard Puzzles, 2011. [Cached copy]
Guo-Niu Han, Enumeration of Standard Puzzles, arXiv:2006.14070 [math.CO], 2020.
Index entries for linear recurrences with constant coefficients, signature (6,-9,4).
FORMULA
From Colin Barker, May 29 2012: (Start)
a(n) = 6*a(n-1) - 9*a(n-2) + 4*a(n-3).
G.f.: (1 - 4*x + 9*x^2)/((1 - x)^2*(1 - 4*x)). (End)
MAPLE
seq(2^(2*n)-2*n, n=0..20);
MATHEMATICA
Table[2^(2n)-2n, {n, 0, 40}] (* or *) LinearRecurrence[{6, -9, 4}, {1, 2, 12}, 40] (* Harvey P. Dale, May 27 2021 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Jorge Coveiro, Dec 26 2004
STATUS
approved