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A175601
7*(10^n-9).
1
7, 637, 6937, 69937, 699937, 6999937, 69999937, 699999937, 6999999937, 69999999937, 699999999937, 6999999999937, 69999999999937, 699999999999937, 6999999999999937, 69999999999999937, 699999999999999937
OFFSET
1,1
FORMULA
G.f.: 7*x*(1 + 80*x)/((1 - x)*(1 - 10*x)). - Vincenzo Librandi, Aug 23 2014
a(n) = 11*a(n-1) - 10*a(n-2). - Vincenzo Librandi, Aug 23 2014
MATHEMATICA
CoefficientList[Series[7 (1 + 80 x)/((1 - x) (1 - 10 x)), {x, 0, 20}], x] (* Vincenzo Librandi, Aug 23 2014 *)
LinearRecurrence[{11, -10}, {7, 637}, 20] (* Harvey P. Dale, Nov 30 2022 *)
PROG
(Magma) [7*(10^n-9): n in [1..20]]; // Vincenzo Librandi, Aug 23 2014
CROSSREFS
Sequence in context: A319033 A182346 A333741 * A246113 A277839 A109542
KEYWORD
nonn
STATUS
approved