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A106659
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Smallest semiprime ending in exactly n 5's.
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0
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15, 55, 1555, 125555, 655555, 1555555, 145555555, 355555555, 8555555555, 85555555555, 155555555555, 1555555555555, 25555555555555, 155555555555555, 17555555555555555, 25555555555555555, 655555555555555555
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(3)=1555 is a term because 1555 is the smallest semiprime ending in exactly three 5's.
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MATHEMATICA
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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 *)
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CROSSREFS
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KEYWORD
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base,nonn
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AUTHOR
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STATUS
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approved
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