A046504 -id:A046504 - cp's OEIS frontend

A046513 Numbers with multiplicative persistence value 4.

77, 177, 268, 277, 286, 348, 355, 377, 378, 379, 384, 387, 397, 438, 446, 464, 467, 476, 477, 483, 489, 498, 535, 553, 557, 575, 628, 644, 647, 668, 674, 677, 678, 682, 686, 687, 699, 717, 727, 737, 738, 739, 746, 747, 755, 764, 767, 768, 771, 772, 773

Offset: 1

Patrick De Geest, Sep 15 1998

			737 -> [ 147 ][ 28 ][ 16 ][ 6 ] -> one digit in four steps.

Robert Israel, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Multiplicative Persistence

Cf. A003001, A014120, A046504.

mp:= proc(n) option remember;
    if n <= 9 then return 0 fi;
    1+procname(convert(convert(n,base,10),`*`))
end proc:
select(mp=4, [$1..1000]); # Robert Israel, Feb 12 2019

pr4Q[n_] := Length[NestWhileList[Times @@ IntegerDigits[#] &, n, # > 9 &]] == 5; Select[Range[773], pr4Q] (* Jayanta Basu, Jun 26 2013 *)

Offset corrected by Robert Israel, Feb 12 2019

A199994 Composite numbers whose multiplicative persistence is 4.

Original entry on oeis.org

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

Jaroslav Krizek, Nov 13 2011

Complement of A046504 with respect to A046513.

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

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

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

cp's OEIS Frontend

A046513 Numbers with multiplicative persistence value 4.

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