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 A165246 a(n) = (10^n+53)/9 1
 7, 17, 117, 1117, 11117, 111117, 1111117, 11111117, 111111117, 1111111117, 11111111117, 111111111117, 1111111111117, 11111111111117, 111111111111117, 1111111111111117, 11111111111111117, 111111111111111117 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n) are also n-1 units followed by a seven LINKS Markus Tervooren, Factorizations of (1)w7 Index to sequences with linear recurrences with constant coefficients, signature (11,-10). FORMULA a(n)=9*a(n-1)-8*a(n-2)+2*10^(n-2) [with a(1)=7, a(2)=17] [From Vincenzo Librandi, Aug 02 2010] a(n)=11*a(n-1)-10*a(n-2). G.f.: -x*(60*x-7)/((x-1)*(10*x-1)). [Colin Barker, Jan 24 2013] EXAMPLE a(3)=9*17-8*7+2*10=117; a(4)=9*117-8*17+2*10^2=1117 [From Vincenzo Librandi, Aug 02 2010] MATHEMATICA Table[FromDigits[PadLeft[{7}, n, 1]], {n, 20}] (* From Harvey P. Dale, Oct 17 2011 *) CROSSREFS Sequence in context: A067185 A205989 A063384 * A118108 A214149 A147643 Adjacent sequences:  A165243 A165244 A165245 * A165247 A165248 A165249 KEYWORD easy,nonn AUTHOR Ivan Panchenko, Sep 10 2009 STATUS approved

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