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A199978
Nonprime numbers whose multiplicative digital root is 0.
2
10, 20, 25, 30, 40, 45, 50, 52, 54, 55, 56, 58, 60, 65, 69, 70, 78, 80, 85, 87, 90, 95, 96, 100, 102, 104, 105, 106, 108, 110, 120, 125, 130, 140, 145, 150, 152, 154, 155, 156, 158, 159, 160, 165, 169, 170, 178, 180, 185, 187, 190, 195, 196, 200, 201, 202
OFFSET
1,1
COMMENTS
Complement of A199977 with respect to A034048.
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
Cf. A199977 (primes whose multiplicative digital root is 0).
Sequence in context: A144140 A361337 A034048 * A342142 A179819 A320522
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Nov 13 2011
STATUS
approved