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Largest semiprime whose prime factors add up to 10^n.
1

%I #7 Mar 08 2015 20:01:51

%S 25,2491,249919,24993439,2499984871,249999996751,24999999992431,

%T 2499999999940951,249999999999995239,24999999999999996031,

%U 2499999999999999964279,249999999999999999946639

%N Largest semiprime whose prime factors add up to 10^n.

%H Lekraj Beedassy, Feb 11 2008, <a href="/A135057/b135057.txt">Table of n, a(n) for n = 1..37</a>

%F a(n) = A124450(n)*(10^n - A124550(n)) {= A137611(n)*A137612(n) for n>1}.

%F a(n) = 100^n/4-(A124049(n))^2. - _Zak Seidov_, Feb 15 2008.

%K nonn

%O 1,1

%A _Lekraj Beedassy_, Feb 11 2008