A199981 Composite numbers whose multiplicative digital root is 2.

12, 21, 26, 34, 62, 112, 121, 126, 134, 143, 162, 216, 232, 261, 278, 279, 287, 297, 299, 314, 322, 341, 369, 371, 376, 396, 398, 413, 447, 469, 474, 496, 612, 621, 637, 639, 649, 666, 693, 694, 713, 728, 729, 731, 736, 744, 763, 782, 792, 872, 893, 927, 936

Offset: 1

Author

Jaroslav Krizek, Nov 13 2011

Keywords

• nonn
• base

Comments

Complement of A199980 with respect to A034049.

Examples

			Number 278 is in sequence because 2*7*8=112, 1*1*2 =2.
		

Crossrefs

Cf. A199980 (primes whose multiplicative digital root is 2).

Cf. A034049 (numbers whose multiplicative digital root is 2).

Programs

Mathematica

t = {}; n = 0; While[Length[t] < 100, n = n + 1; If[! PrimeQ[n], s = n; While[s >= 10, s = Times @@ IntegerDigits[s]]; If[s == 2, AppendTo[t, n]]]]; t (* T. D. Noe, Nov 16 2011 *)