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A140498
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a(n) = 3*a(n-1)-3*a(n-2)+3*a(n-3) with a(0)=1, a(1)=3, a(2)=7.
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0
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1, 3, 7, 15, 33, 75, 171, 387, 873, 1971, 4455, 10071, 22761, 51435, 116235, 262683, 593649, 1341603, 3031911, 6851871, 15484689, 34994187, 79084107, 178723827, 403901721, 912786003, 2062824327, 4661820135, 10535345433, 23809048875, 53806570731, 121598601867
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OFFSET
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0,2
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COMMENTS
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Second differences of A137256.
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LINKS
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Table of n, a(n) for n=0..31.
Index to sequences with linear recurrences with constant coefficients, signature (3,-3,3).
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FORMULA
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G.f.: (1+x^2)/(1-3*x+3*x^2-3*x^3). - Colin Barker, Mar 28 2012
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PROG
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(MAGMA) m:=32; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1+x^2)/(1-3*x+3*x^2-3*x^3))); // Bruno Berselli, Mar 28 2012
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CROSSREFS
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Sequence in context: A146654 A193641 A026701 * A136029 A225338 A101892
Adjacent sequences: A140495 A140496 A140497 * A140499 A140500 A140501
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KEYWORD
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nonn,easy
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AUTHOR
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Paul Curtz, Jun 29 2008
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EXTENSIONS
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More terms from Colin Barker, Mar 28 2012
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STATUS
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approved
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