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%I #8 Mar 30 2012 19:00:24
%S 0,80,976,9904,99952,999952,9999952,99999824,999999536,9999999824,
%T 99999999536,999999999567,9999999999963,99999999999728,
%U 999999999999856,9999999999998896,99999999999999824,999999999999999952,9999999999999999856,99999999999999999568
%N a(n) = the largest n-digit number with exactly 10 divisors, a(n) = 0 if no such number exists.
%C a(n) = the largest n-digit number of the form p^9 or p^4*q (p, q distinct primes), a(n) = 0 if no such number exists.
%F A000005(a(n)) = 10.
%F a(n) >= A182679(n).
%t Table[k=10^n-1; While[k>10^(n-1) && DivisorSigma[0, k] != 10, k--]; If[k==10^(n-1), k=0]; k, {n, 20}]
%Y Cf. A030628, A182679.
%K nonn,base
%O 1,2
%A _Jaroslav Krizek_, Nov 27 2010
%E Extended by _T. D. Noe_, Nov 29 2010
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