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A118692 Semiprimes for which the multiplicative digital root is also a semiprime. 0
4, 6, 9, 14, 22, 33, 39, 74, 82, 86, 91, 93, 119, 122, 123, 133, 141, 161, 213, 217, 218, 221, 249, 267, 289, 298, 319, 321, 346, 377, 382, 386, 391, 411, 417, 422, 437, 466, 471, 473, 478, 481, 489, 611, 626, 634, 662, 674, 679, 681, 697, 721, 734, 737, 746 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..55.

EXAMPLE

39 is in the sequence because (1) it is a semiprime and (2) the multiplicative digital root 4 is also a semiprime.

CROSSREFS

Cf. A001358.

Sequence in context: A073679 A257559 A118689 * A020706 A226271 A137371

Adjacent sequences:  A118689 A118690 A118691 * A118693 A118694 A118695

KEYWORD

base,nonn

AUTHOR

Luc Stevens (lms022(AT)yahoo.com), May 20 2006

STATUS

approved

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Last modified April 20 03:36 EDT 2019. Contains 322294 sequences. (Running on oeis4.)