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%I #14 Sep 10 2023 12:15:48
%S 111111111,222222222,333333333,444444444,555555555,666666666,
%T 777777777,888888888,999999999,1111111110,1222222221,1333333332,
%U 1444444443,1555555554,1666666665,1777777776,1888888887,1999999998,2111111109
%N 9*n*12345679.
%H Vincenzo Librandi, <a href="/A172525/b172525.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,-1).
%F a(n) = 2*a(n-1)-a(n-2). - _Colin Barker_, Aug 20 2014
%F G.f.: 111111111*x / (x-1)^2. - _Colin Barker_, Aug 20 2014
%t Table[9 n 12345679, {n, 1, 20}] (* _Vincenzo Librandi_, Aug 20 2014 *)
%t LinearRecurrence[{2,-1},{111111111,222222222},20] (* _Harvey P. Dale_, Sep 10 2023 *)
%o (Magma) [9*n*12345679: n in [1..20]]; // _Vincenzo Librandi_, Aug 20 2014
%o (PARI) Vec(111111111*x/(x-1)^2 + O(x^100)) \\ _Colin Barker_, Aug 20 2014
%Y Cf. A021085.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Feb 06 2010
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