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Largest n-digit number - largest n-digit triangular number.
7

%I #9 May 16 2017 14:30:18

%S 3,8,9,129,318,1008,2843,8988,38439,121089,42708,88208,2034819,

%T 1749819,2235879,104271309,447194784,1234742858,2234186964,3266133123,

%U 22172578524,114481278033,204796672749,841526085621,355055477499

%N Largest n-digit number - largest n-digit triangular number.

%H Harvey P. Dale, <a href="/A095866/b095866.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = 10^n - 1 - A095864(n).

%t lndt[n_]:=Module[{c=Floor[(Sqrt[8*10^n+1]-1)/2]},(c(c+1))/2]; Join[{3}, Table[ 10^n-1-lndt[n],{n,2,30}]] (* _Harvey P. Dale_, May 16 2017 *)

%Y Cf. A068092, A068093, A068094, A095863, A095864, A095865.

%K base,easy,nonn

%O 1,1

%A _Ray Chandler_, Jun 28 2004