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

1,1

Comments

Complement of A046504 with respect to A046513.

Links

Table of n, a(n) for n=1..52.

Example

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

Mathematica

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

Crossrefs

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

Sequence in context: A075253 A217790 A046513 * A043518 A044409 A044790

Adjacent sequences: A199991 A199992 A199993 * A199995 A199996 A199997

Keyword

nonn,base

Author

Jaroslav Krizek, Nov 13 2011

Status

approved