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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified March 28 15:03 EDT 2020. Contains 333089 sequences. (Running on oeis4.)