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A165746
a(n) = 3 - 2*3^n.
2
1, -3, -15, -51, -159, -483, -1455, -4371, -13119, -39363, -118095, -354291, -1062879, -3188643, -9565935, -28697811, -86093439, -258280323, -774840975, -2324522931, -6973568799, -20920706403, -62762119215, -188286357651
OFFSET
0,2
FORMULA
G.f.: (1-7*x)/(1 - 4*x + 3*x^2).
a(n) = 3 - A008776(n).
a(n) = 4*a(n-1) - 3*a(n-2) for n > 1; a(0)=1, a(1)=-3.
a(n) = Sum_{k=0..n} A112555(n,k)*(-4)^(n-k).
a(n) = 3*a(n-1) - 6. - Vincenzo Librandi, Nov 03 2011
MATHEMATICA
Table[3-2*3^n, {n, 0, 30}] (* or *) LinearRecurrence[{4, -3}, {1, -3}, 30] (* Harvey P. Dale, Aug 29 2024 *)
PROG
(Magma) [3-2*3^n : n in [0..30]]; // Vincenzo Librandi, Nov 03 2011
CROSSREFS
Sequence in context: A012203 A112586 A043005 * A248122 A118126 A282464
KEYWORD
sign,easy
AUTHOR
Philippe Deléham, Sep 26 2009
STATUS
approved