A199994 Composite numbers whose multiplicative persistence is 4.

77, 177, 268, 286, 348, 355, 377, 378, 384, 387, 438, 446, 464, 476, 477, 483, 489, 498, 535, 553, 575, 628, 644, 668, 674, 678, 682, 686, 687, 699, 717, 737, 738, 746, 747, 755, 764, 767, 768, 771, 772, 774, 776, 777, 778, 783, 786, 788, 793, 826, 834, 837

Offset: 1

Author

Jaroslav Krizek, Nov 13 2011

Keywords

• nonn
• base

Comments

Complement of A046504 with respect to A046513.

Examples

			77 -> [ 49 ][ 36 ][ 18 ][ 8 ] -> one digit in four steps.
		

Crossrefs

Cf. A046504 (primes whose multiplicative persistence is 4).

Programs

Mathematica

persistence[n_] := Module[{cnt = 0, k = n}, While[k > 9, cnt++; k = Times @@ IntegerDigits[k]]; cnt]; Select[Range[1000], ! PrimeQ[#] && persistence[#] == 4 &]