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Search: id:A083694
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| 0, 2, 4, 18, 56, 202, 684, 2378, 8176, 28242, 97364, 335938, 1158696, 3997082, 13787644, 47560698, 164059616, 565922722, 1952143524, 6733900658, 23228518936, 80126541162, 276395677004, 953424059818, 3288826504656
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OFFSET
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0,2
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COMMENT
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A002533(n)/a(n) converges to sqrt(3/2), n>0. a(n)=2*A002533(n-1)+a(n-1).
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FORMULA
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G.f.: 2x/(1-2x-5x^2). a(n)=(1/sqrt(6))[(1+sqrt(6))^n-(1-sqrt(6))^n].
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MATHEMATICA
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CoefficientList[Series[2x/(1-2x-5x^2), {x, 0, 25}], x]
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CROSSREFS
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Sequence in context: A045664 A106520 A093045 this_sequence A009679 A007727 A052689
Adjacent sequences: A083691 A083692 A083693 this_sequence A083695 A083696 A083697
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KEYWORD
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easy,nonn
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AUTHOR
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Mario Catalani (mario.catalani(AT)unito.it), May 03 2003
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