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 A046508 #21 Feb 16 2025 08:32:39 %S A046508 2678789,2687879,2687897,2688797,2688977,2689877,2697887,2768789, %T A046508 2768897,2769887,2778689,2786789,2787689,2788769,2798687,2798867, %U A046508 2868779,2868977,2876789,2876879,2878679,2878697,2878769,2879687 %N A046508 Primes with multiplicative persistence value 8. %H A046508 Daniel Mondot, <a href="/A046508/b046508.txt">Table of n, a(n) for n = 1..10000</a> (terms 1..9001 from Harvey P. Dale) %H A046508 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence</a> %e A046508 2678789 -> [ 338688 ][ 27648 ][ 2688 ][ 768 ][ 336 ][ 54 ][ 20 ][ 0 ] -> one digit in eight steps. %t A046508 mp8Q[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]==9; Select[ Prime[ Range[210000]],mp8Q] (* _Harvey P. Dale_, Mar 30 2019 *) %Y A046508 Intersection of A000040 and A046517. %Y A046508 Cf. A046500. %K A046508 nonn,base %O A046508 1,1 %A A046508 _Patrick De Geest_, Sep 15 1998