A106659 Smallest semiprime ending in exactly n 5's.

15, 55, 1555, 125555, 655555, 1555555, 145555555, 355555555, 8555555555, 85555555555, 155555555555, 1555555555555, 25555555555555, 155555555555555, 17555555555555555, 25555555555555555, 655555555555555555

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Example

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

Mathematica

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 *)

Crossrefs

Sequence in context: A082235 A219592 A104724 * A119136 A036522 A227219

Adjacent sequences: A106656 A106657 A106658 * A106660 A106661 A106662

Keyword

base,nonn

Author

Shyam Sunder Gupta, May 12 2005

Status

approved