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A175237 2*(10^n - 7). 1
6, 186, 1986, 19986, 199986, 1999986, 19999986, 199999986, 1999999986, 19999999986, 199999999986, 1999999999986, 19999999999986, 199999999999986, 1999999999999986, 19999999999999986, 199999999999999986 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..100

FORMULA

G.f.: 6*x*(1 + 20*x)/((1-x)*(1-10*x)). - Vincenzo Librandi, Apr 26 2014

MATHEMATICA

Join[{6}, Table[FromDigits[Join[{1}, PadLeft[{8, 6}, n, 9]]], {n, 2, 20}]] (* Harvey P. Dale, Mar 22 2012 *)

CoefficientList[Series[6 (1 + 20 x)/((1 - x) (1 - 10 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Apr 26 2014 *)

PROG

(MAGMA) [2*(10^n-7): n in [1..20]]; // Vincenzo Librandi, Apr 26 2014

CROSSREFS

Sequence in context: A012181 A012224 A274272 * A222335 A037298 A272467

Adjacent sequences:  A175234 A175235 A175236 * A175238 A175239 A175240

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 15 2010

STATUS

approved

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Last modified September 21 05:55 EDT 2020. Contains 337267 sequences. (Running on oeis4.)