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A124191 a(n)=((2 + 3Sqrt[2])^n - (2 - 3Sqrt[2])^n)/(2Sqrt[2]). 0
0, 3, 12, 90, 528, 3372, 20880, 130728, 815232, 5091120, 31777728, 198386592, 1238434560, 7731150528, 48262685952, 301286851200, 1880825008128, 11741315949312, 73296813911040 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

Index entries for linear recurrences with constant coefficients, signature (4,14).

FORMULA

a(0)=0, a(1)=3, a(n)=4*a(n-1)+14*a(n-2) for n>=2 . G.f.:3x/(1-4*x-14*x^2) - Philippe Deléham, Dec 12 2006

a(n)=-(1/4)*sqrt(2)*[2-3*sqrt(2)]^n+(1/4)*[2+3*sqrt(2)]^n*sqrt(2), with n>=0 [From Paolo P. Lava, Oct 07 2008]

MATHEMATICA

Expand[Table[((2 + 3Sqrt[2])^n - (2 - 3Sqrt[2])^n)/(2Sqrt[2]), {n, 0, 30}]] (*Artur Jasinski*)

CROSSREFS

Sequence in context: A266788 A039305 A174463 * A065087 A305870 A058337

Adjacent sequences:  A124188 A124189 A124190 * A124192 A124193 A124194

KEYWORD

nonn,easy

AUTHOR

Artur Jasinski, Dec 10 2006

STATUS

approved

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Last modified September 16 08:36 EDT 2019. Contains 327091 sequences. (Running on oeis4.)