A198377 Smallest nonprime number with multiplicative persistence n.

0, 10, 25, 39, 77, 679, 6788, 68889, 2677889, 26888999, 3778889989, 277777788888899

Offset: 0

Author

Jaroslav Krizek, Oct 23 2011

Keywords

• nonn
• base

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.

Examples

			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).