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A190943
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a(n) = 8*a(n-1) + 27*a(n-2), with a(0)=0, a(1)=1.
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2
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0, 1, 8, 91, 944, 10009, 105560, 1114723, 11767904, 124240753, 1311659432, 13847775787, 146197010960, 1543466033929, 16295047567352, 172033963454899, 1816237991957696, 19174820948943841, 202436993374408520, 2137216112616751867
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OFFSET
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0,3
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LINKS
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Bruno Berselli, Table of n, a(n) for n = 0..300
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FORMULA
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G.f.: x/(1-8*x-27*x^2).
a(n) = ((4+sqrt(43))^n-(4-sqrt(43))^n)/(2*sqrt(43)).
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MATHEMATICA
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a = {0, 1}; Do[AppendTo[a, 8 a[[-1]] + 27 a[[-2]]], {18}]; a (* Bruno Berselli, Dec 26 2012 *)
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PROG
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(Maxima) a[0]:0$ a[1]:1$ a[n]:=8*a[n-1]+27*a[n-2]$ makelist(a[n], n, 0, 17);
(MAGMA) [n le 2 select n-1 else 8*Self(n-1)+27*Self(n-2): n in [1..17]];
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CROSSREFS
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Cf. A000045, A046717, A015533 (for type of recurrence).
Cf. A015611, A190441 (for type of closed formula).
Sequence in context: A034667 A116149 A184709 * A180912 A220573 A187157
Adjacent sequences: A190940 A190941 A190942 * A190944 A190945 A190946
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KEYWORD
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nonn,easy
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AUTHOR
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Bruno Berselli, May 24 2011
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STATUS
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approved
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