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Search: id:A117080
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| A117080 |
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a(n) = 2a(n-1)+a(n-3)+1 with a(1)=1, a(2)=3, a(3)=8. |
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+0
1
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| 1, 3, 8, 18, 40, 89, 197, 435, 960, 2118, 4672, 10305, 22729, 50131, 110568, 243866, 537864, 1186297, 2616461, 5770787, 12727872, 28072206, 61915200, 136558273, 301188753, 664292707, 1465143688, 3231476130, 7127244968, 15719633625, 34670743381, 76468731731
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OFFSET
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1,2
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FORMULA
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a(n)=3*a(n-1)-2*a(n-2)+a(n-3)-a(n-4). G.f.: x*(-1-x^2+x^3)/((1-x)*(x^3+2*x-1)). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 25 2009]
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CROSSREFS
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Sequence in context: A026657 A036384 A080692 this_sequence A066425 A026679 A026756
Adjacent sequences: A117077 A117078 A117079 this_sequence A117081 A117082 A117083
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com), following a suggestion of Franklin T. Adams-Watters, Apr 20 2006
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