A199993 Composite numbers whose multiplicative persistence is 3.

39, 49, 55, 57, 66, 68, 69, 74, 75, 78, 86, 87, 88, 93, 94, 95, 96, 98, 147, 155, 159, 166, 168, 169, 174, 175, 178, 186, 187, 188, 189, 194, 195, 196, 198, 236, 238, 246, 247, 248, 249, 264, 266, 267, 272, 274, 276, 279, 284, 288, 289, 292, 294, 297, 298, 299

Offset

1,1

Comments

Complement of A046503 with respect to A046512.

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Eric Weisstein's World of Mathematics, Multiplicative Persistence

Formula

{ A046512 } minus { A046503 }.

Example

147 -> 1 * 4 * 7 -> [ 28 ] -> 2 * 8 -> [ 16 ] -> 1 * 6 -> [ 6 ] -> one digit in three steps.

Mathematica

Select[Range[300], CompositeQ[#]&&Length[NestWhileList[Times@@ IntegerDigits[ #]&, #, #>9&]] == 4&] (* Harvey P. Dale, Mar 29 2023 *)

Crossrefs

Cf. A046503 (primes whose multiplicative persistence is 3).

Sequence in context: A064399 A235151 A050439 * A181488 A020305 A216978

Adjacent sequences: A199990 A199991 A199992 * A199994 A199995 A199996

Keyword

nonn,base

Author

Jaroslav Krizek, Nov 13 2011

Status

approved