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Smallest semiprime ending in exactly n 5's.
0

%I #4 Mar 29 2015 11:41:31

%S 15,55,1555,125555,655555,1555555,145555555,355555555,8555555555,

%T 85555555555,155555555555,1555555555555,25555555555555,

%U 155555555555555,17555555555555555,25555555555555555,655555555555555555

%N Smallest semiprime ending in exactly n 5's.

%e a(3)=1555 is a term because 1555 is the smallest semiprime ending in exactly three 5's.

%t ssp[n_]:=Module[{k=0,c=FromDigits[Table[5,{n}]]},While[PrimeOmega[ k*10^n+ c]!=2,k++];k*10^n+c]; Array[ssp,20] (* _Harvey P. Dale_, Mar 29 2015 *)

%K base,nonn

%O 1,1

%A _Shyam Sunder Gupta_, May 12 2005