OFFSET
1,1
COMMENTS
Factorials 0! and 1! are not considered distinct.
EXAMPLE
721 = 6!+1! = 7*103.
MATHEMATICA
semipQ[n_] := Plus @@ Last /@ FactorInteger[n] == 2; fac=Range[10]!; lst={}; Do[ n = Plus@@(fac*IntegerDigits[k, 2, 10]); If[semipQ[n], AppendTo[lst, n]], {k, 2^10-1}]; Union[lst]
CROSSREFS
KEYWORD
nonn
AUTHOR
Giovanni Resta, Jan 27 2006
STATUS
approved