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%I #20 Apr 14 2023 07:55:20
%S 0,63,693,6993,69993,699993,6999993,69999993,699999993,6999999993,
%T 69999999993,699999999993,6999999999993,69999999999993,
%U 699999999999993,6999999999999993,69999999999999993,699999999999999993,6999999999999999993,69999999999999999993,699999999999999999993
%N a(n) = 7*(10^n - 1).
%C Original definition: a(n) = k where R(k+7) = 7.
%H G. C. Greubel, <a href="/A086578/b086578.txt">Table of n, a(n) for n = 0..500</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-10).
%F a(n) = 7*9*A002275(n) = 7*A002283(n).
%F R(a(n)) = A086575(n).
%F From _Chai Wah Wu_, Jul 08 2016: (Start)
%F a(n) = 11*a(n-1) - 10*a(n-2) for n > 1.
%F G.f.: 63*x/((1 - x)*(1 - 10*x)). (End)
%F E.g.f.: 7*(exp(10*x) - exp(x)). - _G. C. Greubel_, Apr 14 2023
%t LinearRecurrence[{11,-10}, {0,63}, 31] (* _G. C. Greubel_, Apr 14 2023 *)
%o (Magma) [7*(10^n -1): n in [0..20]]; // _G. C. Greubel_, Apr 14 2023
%o (SageMath) [7*(10^n -1) for n in range(21)] # _G. C. Greubel_, Apr 14 2023
%Y Cf. A002275, A004086 (R(n)).
%Y One of family of sequences of form a(n) = k, where R(k+m) = m, m=1 to 9; m=1: A002283, m=2: A086573, m=3: A086574, m=4: A086575, m=5: A086576, m=6: A086577, m=7: A086578, m=8: A086579, m=9: A086580.
%Y Sequences of the form m*10^n - 7: 3*A033175 (m=1, 10), A086943 (m=3), 3*A185127 (m=4), this sequence (m=7), A100412 (m=8).
%K nonn
%O 0,2
%A _Ray Chandler_, Jul 22 2003
%E Edited by _Jinyuan Wang_, Aug 04 2021