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A189743 a(1)=4,  a(2)=4, a(n)=4*a(n-1) + 4*a(n-2) 13
4, 4, 32, 144, 704, 3392, 16384, 79104, 381952, 1844224, 8904704, 42995712, 207601664, 1002389504, 4839964672, 23369416704, 112837525504, 544827768832, 2630661177344, 12701955784704, 61330467848192, 296129694531584, 1429840649519104, 6903881376202752 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..100

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

FORMULA

a(n) = 2*((2+2*sqrt(2))^(n-1)+(2-2*sqrt(2))^(n-1))+1/2*sqrt(2)*((2-2*sqrt(2))^(n-1)-(2+2 *sqrt(2))^(n-1)). - Paolo P. Lava, May 24 2011

G.f.: 4*x*(1-3*x)/(1-4*x-4*x^2). - Bruno Berselli, May 24 2011

MATHEMATICA

LinearRecurrence[{4, 4}, {4, 4}, 40]

PROG

(Maxima) a[1]:4$ a[2]:4$ a[n]:=4*a[n-1]+4*a[n-2]$ makelist(a[n], n, 1, 24);  [Bruno Berselli, May 24 2011]

CROSSREFS

Cf. A000045, A000079, A105476, A159612, A080040, A135522, A103435, A189732, A189734, A189735, A189736, A189737, A189738, A189739, A189741, A189742, A189744, A189745, A189746, A189747, A189748, A189749.

Sequence in context: A271003 A217310 A298681 * A089542 A222285 A222504

Adjacent sequences:  A189740 A189741 A189742 * A189744 A189745 A189746

KEYWORD

nonn

AUTHOR

Harvey P. Dale, Apr 26 2011

STATUS

approved

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Last modified October 18 03:25 EDT 2021. Contains 348065 sequences. (Running on oeis4.)