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 A046511 #26 Feb 16 2025 08:32:39 %S A046511 25,26,27,28,29,34,35,36,37,38,43,44,45,46,48,52,53,54,56,58,62,63,64, %T A046511 65,67,72,73,76,82,83,84,85,92,99,125,126,127,128,129,134,135,136,137, %U A046511 138,143,144,145,146,148,152,153,154,156,158,162,163,164,165,167,172 %N A046511 Numbers with multiplicative persistence value 2. %H A046511 Daniel Mondot, <a href="/A046511/b046511.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..3000 from Vincenzo Librandi) %H A046511 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence</a> %e A046511 129 -> [ 18 ] -> [ 8 ] = one digit in two steps. %t A046511 mpQ[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==3; Select[Range[200], mpQ] (* _Harvey P. Dale_, Apr 12 2014 *) %o A046511 (Python) %o A046511 from math import prod %o A046511 def pd(n): return prod(map(int, str(n))) %o A046511 def ok(n): return n > 9 and (p := pd(n)) > 9 and pd(p) < 10 %o A046511 print([k for k in range(173) if ok(k)]) # _Michael S. Branicky_, Jan 16 2022 %Y A046511 Cf. A003001, A014120, A046502. %K A046511 nonn,base %O A046511 1,1 %A A046511 _Patrick De Geest_, Sep 15 1998