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A093852 a(n) = 10^(n-1) - 1 + n*floor(9*10^(n-1)/(n+1)).

%I A093852 #15 Sep 08 2022 08:45:13
%S A093852 4,69,774,8199,84999,871425,8874999,89999999,909999999,9181818179,
%T A093852 92499999999,930769230759,9357142857140,93999999999999,
%U A093852 943749999999999,9470588235294111,94999999999999999,952631578947368403,9549999999999999999,95714285714285714279
%N A093852 a(n) = 10^(n-1) - 1 + n*floor(9*10^(n-1)/(n+1)).
%C A093852 This sequence is the main diagonal of A093850.
%H A093852 G. C. Greubel, <a href="/A093852/b093852.txt">Table of n, a(n) for n = 1..995</a>
%e A093852 n-th row of the following triangle contains n uniformly located n-digit numbers. i.e. n terms of an arithmetic progression with 10^(n-1)-1 as the term preceding the first term and (n+1)-th term is the largest possible n-digit term.
%e A093852 Given the triangle defined in A093850:
%e A093852 ...4;
%e A093852 ..39   69;
%e A093852 .324  549  774;
%e A093852 2799 4599 6399 8199.....
%e A093852 then this sequence is the leading diagonal.
%p A093852 A093852 := proc(n)
%p A093852         r := n ;
%p A093852         10^(n-1)-1+r*floor(9*10^(n-1)/(n+1)) ;
%p A093852 end proc:
%p A093852 seq(A093852(n),n=1..50) ; # _R. J. Mathar_, Oct 01 2011
%t A093852 Table[10^(n-1) -1 +n*Floor[9*10^(n-1)/(n+1)], {n,25}] (* _G. C. Greubel_, Mar 21 2019 *)
%o A093852 (PARI) {a(n) = 10^(n-1) -1 +n*floor(9*10^(n-1)/(n+1))}; \\ _G. C. Greubel_, Mar 21 2019
%o A093852 (Magma) [10^(n-1) -1 +n*Floor(9*10^(n-1)/(n+1)): n in [1..25]]; // _G. C. Greubel_, Mar 21 2019
%o A093852 (Sage) [10^(n-1) -1 +n*floor(9*10^(n-1)/(n+1)) for n in (1..25)] # _G. C. Greubel_, Mar 21 2019
%Y A093852 Cf. A093846, A093847, A061772, A093450, A072875.
%K A093852 easy,nonn
%O A093852 1,1
%A A093852 _Amarnath Murthy_, Apr 18 2004