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A109002
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Maximal difference between two n-digit numbers.
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6
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9, 89, 899, 8999, 89999, 899999, 8999999, 89999999, 899999999, 8999999999, 89999999999, 899999999999, 8999999999999, 89999999999999, 899999999999999
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| a(n) = A061601(A178500(n-1)). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 28 2010]
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..200
Index to sequences with linear recurrences with constant coefficients, signature (11,-10).
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FORMULA
| a(n) = (10^n -1) - 10^(n-1), n >1.
a(n+1) = 10*a(n) + 9. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 28 2010]
G.f.: 9*x -x^2*(-89+80*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Oct 29 2011
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EXAMPLE
| a(1) =9-0 =9, a(4) = 9999-1000 = 8999.
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PROG
| (MAGMA) [9], [9*10^n-1: n in [1..30]]; // Vincenzo Librandi, Oct 29 2011
(PARI) a(n)=if(n>1, (10^n-1)-10^(n-1), 9) \\ Charles R Greathouse IV, Oct 29 2011
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CROSSREFS
| Sequence in context: A072256 A138288 A059482 * A142991 A152267 A082147
Adjacent sequences: A108999 A109000 A109001 * A109003 A109004 A109005
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KEYWORD
| base,easy,nonn
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AUTHOR
| Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 14 2005
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