This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A046513 #17 Feb 16 2025 08:32:39 %S A046513 77,177,268,277,286,348,355,377,378,379,384,387,397,438,446,464,467, %T A046513 476,477,483,489,498,535,553,557,575,628,644,647,668,674,677,678,682, %U A046513 686,687,699,717,727,737,738,739,746,747,755,764,767,768,771,772,773 %N A046513 Numbers with multiplicative persistence value 4. %H A046513 Robert Israel, <a href="/A046513/b046513.txt">Table of n, a(n) for n = 1..10000</a> %H A046513 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence</a> %e A046513 737 -> [ 147 ][ 28 ][ 16 ][ 6 ] -> one digit in four steps. %p A046513 mp:= proc(n) option remember; %p A046513 if n <= 9 then return 0 fi; %p A046513 1+procname(convert(convert(n,base,10),`*`)) %p A046513 end proc: %p A046513 select(mp=4, [$1..1000]); # _Robert Israel_, Feb 12 2019 %t A046513 pr4Q[n_] := Length[NestWhileList[Times @@ IntegerDigits[#] &, n, # > 9 &]] == 5; Select[Range[773], pr4Q] (* _Jayanta Basu_, Jun 26 2013 *) %Y A046513 Cf. A003001, A014120, A046504. %K A046513 nonn,base %O A046513 1,1 %A A046513 _Patrick De Geest_, Sep 15 1998 %E A046513 Offset corrected by _Robert Israel_, Feb 12 2019