OFFSET
1,1
EXAMPLE
Number 58 is in sequence because 5*8 = 40, 4*0 = 0.
MATHEMATICA
digRoot[n_] := Module[{k = n}, While[k > 9, k = Times @@ IntegerDigits[k]]; k]; Select[Range[300], ! PrimeQ[#] && digRoot[#] == 0 &] (* T. D. Noe, Nov 23 2011 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Nov 13 2011
STATUS
approved