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A198377
Smallest nonprime number with multiplicative persistence n.
0
0, 10, 25, 39, 77, 679, 6788, 68889, 2677889, 26888999, 3778889989, 277777788888899
OFFSET
0,2
COMMENTS
Probably finite sequence. The multiplicative persistence of a number is the number of times you need to multiply the digits together before reaching a single digit.
EXAMPLE
For n=4, a(4) = 39 because 39 is the smallest nonprime number with multiplicative persistence 3: 39 -> 27 -> 14 -> 4.
CROSSREFS
Cf. A046500 (smallest prime with multiplicative persistence n).
Sequence in context: A087473 A014120 A003001 * A038350 A003344 A345853
KEYWORD
nonn,base
AUTHOR
Jaroslav Krizek, Oct 23 2011
STATUS
approved