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A037182
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a(n) = 10^n*(10^n-1) / 2.
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2
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0, 45, 4950, 499500, 49995000, 4999950000, 499999500000, 49999995000000, 4999999950000000, 499999999500000000, 49999999995000000000, 4999999999950000000000, 499999999999500000000000, 49999999999995000000000000, 4999999999999950000000000000
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OFFSET
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0,2
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COMMENTS
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Sum of all numbers with <= n digits.
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LINKS
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FORMULA
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a(n) = 110*a(n-1) - 1000*a(n-2) for n > 1.
G.f.: 45*x/((10*x - 1)*(100*x - 1)). (End)
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MATHEMATICA
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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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