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%I #29 Sep 08 2022 08:45:51
%S 9,49,961,9409,97969,994009,9840769,99460729,999002449,9998200081,
%T 99996985729,999966000289,9999995824729,99999820000081,
%U 999997874844049,9999997800000121,99999977853408361,999999874000003969,9999999828172082689,99999999340000001089
%N Largest n-digit number with 3 divisors.
%C Because every number with exactly three divisors must be the square of a prime, the last digit of each term in this sequence is either 1 or 9. - _Harvey P. Dale_, Aug 18 2011 [with thanks to _Ant King_ and _Christopher Hunt Gribble_]
%H Charles R Greathouse IV, <a href="/A175734/b175734.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A132153(n)^2.
%t Join[{9},Table[NextPrime[Sqrt[10^n-1],-1]^2,{n,2,20}]](* _Harvey P. Dale_, Aug 18 2011 *)
%o (Magma) A175734 := func<n|PreviousPrime(Isqrt(10^n)+1)^2>; // _Jason Kimberley_, Aug 18 2011
%o (PARI) A175734(n)=precprime(sqrtint(10^n))^2 \\ _M. F. Hasler_, Aug 18 2011
%Y Cf. A131581, A132153, A136582, A175733.
%K nonn,base
%O 1,1
%A _Jaroslav Krizek_, Aug 24 2010
%E a(14)-a(20) from _Harvey P. Dale_, Aug 18 2011
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