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A060072
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a(n) = (n^(n-1) - 1)/(n-1) for n>1, a(1) = 0.
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16
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0, 1, 4, 21, 156, 1555, 19608, 299593, 5380840, 111111111, 2593742460, 67546215517, 1941507093540, 61054982558011, 2085209001813616, 76861433640456465, 3041324492229179280, 128583032925805678351, 5784852794328402307380, 275941052631578947368421
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OFFSET
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1,3
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COMMENTS
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(n-1)-digit repunits in base n written in decimal.
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LINKS
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FORMULA
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EXAMPLE
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a(10)=111111111; i.e., just nine 1's (converted from base 10 to decimal).
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MATHEMATICA
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Join[{0}, Array[(#^(#-1)-1)/(#-1)&, 20, 2]] (* Harvey P. Dale, Jun 04 2013 *)
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PROG
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(PARI) a(n) = if (n==1, 0, (n^(n - 1) - 1)/(n - 1)); \\ Harry J. Smith, Jul 01 2009
(Magma) [0] cat [ (n^(n-1) -1)/(n-1) : n in [2..25]]; // G. C. Greubel, Aug 15 2022
(SageMath) [0]+[(n^(n-1) -1)/(n-1) for n in (2..25)] # G. C. Greubel, Aug 15 2022
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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