

A199981


Composite numbers whose multiplicative digital root is 2.


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
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OFFSET

1,1


COMMENTS

Complement of A199980 with respect to A034049.


LINKS

Table of n, a(n) for n=1..53.


EXAMPLE

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


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 *)


CROSSREFS

Cf. A199980 (primes whose multiplicative digital root is 2).
Cf. A034049 (numbers whose multiplicative digital root is 2).
Sequence in context: A132132 A248378 A327297 * A274347 A316266 A179899
Adjacent sequences: A199978 A199979 A199980 * A199982 A199983 A199984


KEYWORD

nonn,base


AUTHOR

Jaroslav Krizek, Nov 13 2011


STATUS

approved



