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 A170955 a(n) = 10^n - 9. 6
 1, 91, 991, 9991, 99991, 999991, 9999991, 99999991, 999999991, 9999999991, 99999999991, 999999999991, 9999999999991, 99999999999991, 999999999999991, 9999999999999991, 99999999999999991, 999999999999999991 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Column 10 of A193871. - Omar E. Pol, Aug 22 2011 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..100 Index entries for linear recurrences with constant coefficients, signature (11,-10). FORMULA a(n) = 10*a(n-1) + 81 for n>1, a(1)=1. G.f.: x*(1+80*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Aug 24 2011 MATHEMATICA CoefficientList[Series[(1 + 80*x)/(1 - 11*x + 10*x^2), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 06 2013 *) LinearRecurrence[{11, -10}, {1, 91}, 20] (* Harvey P. Dale, Aug 20 2015 *) 10^Range[1, 25] - 9 (* Vincenzo Librandi, Jan 03 2016 *) PROG (MAGMA) [10^n-9: n in [1..30]]; // Vincenzo Librandi, Feb 06 2013 (PARI) a(n)=10^n-9 \\ Charles R Greathouse IV, Oct 07 2015 CROSSREFS Cf. A093177. Sequence in context: A254519 A185375 A036526 * A020316 A221815 A195221 Adjacent sequences:  A170952 A170953 A170954 * A170956 A170957 A170958 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Feb 26 2010 EXTENSIONS Typo in formula corrected by Jon E. Schoenfield, Jun 19 2010 STATUS approved

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Last modified May 26 14:46 EDT 2020. Contains 334626 sequences. (Running on oeis4.)