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A177109
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a(n) = 4*(10^n-5).
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1
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20, 380, 3980, 39980, 399980, 3999980, 39999980, 399999980, 3999999980, 39999999980, 399999999980, 3999999999980, 39999999999980, 399999999999980, 3999999999999980, 39999999999999980, 399999999999999980
(list;
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refs;
listen;
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text;
internal format)
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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G.f.: 20*x*(1+8*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Jan 06 2011
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MAPLE
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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