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A084222
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a(n)=-2a(n-1)+3a(n-2), with a(0)=1, a(1)=2.
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5
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1, 2, -1, 8, -19, 62, -181, 548, -1639, 4922, -14761, 44288, -132859, 398582, -1195741, 3587228, -10761679, 32285042, -96855121, 290565368, -871696099, 2615088302, -7845264901, 23535794708, -70607384119, 211822152362, -635466457081, 1906399371248
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OFFSET
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0,2
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LINKS
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Table of n, a(n) for n=0..27.
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FORMULA
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Binomial transform is A084221.
a(n)=(5-(-3)^n)/4; G.f.: (1+4x)/((1-x)(1+3x)); E.g.f. : (5exp(x)-exp(-3x))/4.
For n > 1, |a(n) - a(n+1)| = 3^n. - Amarnath Murthy and Meenakshi Srikanth (amarnath_murthy(AT)yahoo.com), Jul 15 2003; corrected by Philippe DELEHAM, Dec 16 2007
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MATHEMATICA
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a=1; lst={1, 2, a}; Do[a=3^n-a; AppendTo[lst, a], {n, 2, 5!}]; lst (*All Absolute values Only!*) [From Vladimir Joseph Stephan Orlovsky, Sep 13 2009]
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CROSSREFS
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Sequence in context: A012966 A168244 A009828 * A160602 A160626 A052312
Adjacent sequences: A084219 A084220 A084221 * A084223 A084224 A084225
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KEYWORD
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easy,sign
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AUTHOR
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Paul Barry, May 21 2003
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STATUS
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approved
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