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 A094797 Number of times 1 is used in writing out all numbers 1 through 10^n. 0
 1, 2, 21, 301, 4001, 50001, 600001, 7000001, 80000001, 900000001, 10000000001, 110000000001, 1200000000001, 13000000000001, 140000000000001, 1500000000000001, 16000000000000001, 170000000000000001, 1800000000000000001, 19000000000000000001 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Index entries for linear recurrences with constant coefficients, signature (21,-120,100). FORMULA a(n) = n*10^(n-1) + 1. a(n) = 21*a(n-1)-120*a(n-2)+100*a(n-3). - Colin Barker, May 23 2014 G.f.: -(99*x^2-19*x+1) / ((x-1)*(10*x-1)^2). - Colin Barker, May 23 2014 MATHEMATICA Table[ n*10^(n - 1) + 1, {n, 0, 17}] (* Robert G. Wilson v, Jun 15 2004 *) PROG (PARI) Vec(-(99*x^2-19*x+1)/((x-1)*(10*x-1)^2) + O(x^100)) \\ Colin Barker, May 23 2014 CROSSREFS Cf. A072290, A078427. Sequence in context: A266969 A229036 A097627 * A234525 A230382 A196629 Adjacent sequences:  A094794 A094795 A094796 * A094798 A094799 A094800 KEYWORD base,nonn,easy AUTHOR Lekraj Beedassy, Jun 11 2004 EXTENSIONS More terms from Robert G. Wilson v, Jun 15 2004 Further terms from Colin Barker, May 23 2014 STATUS approved

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Last modified July 20 22:54 EDT 2019. Contains 325189 sequences. (Running on oeis4.)