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 A046500 #24 Mar 10 2025 11:51:02
%S A046500 2,11,29,47,277,769,8867,186889,2678789,26899889,3778888999,
%T A046500 277777788888989
%N A046500 Smallest prime with multiplicative persistence n.
%C A046500 The persistence of a number is the number of times you need to multiply the digits together before reaching a single digit.
%H A046500 Shyam Sunder Gupta, <a href="https://doi.org/10.1007/978-981-97-2465-9_1">Digital Root Wonders</a>, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 1, 1-28.
%H A046500 Carlos Rivera, <a href="http://www.primepuzzles.net/puzzles/puzz_022.htm">Puzzle 22. Primes & Persistence</a>, The Prime Puzzles & Problems Connection.
%H A046500 N. J. A. Sloane, <a href="http://neilsloane.com/doc/persistence.html">The persistence of a number</a>, J. Recreational Math., 6 (1973), 97-98.
%H A046500 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MultiplicativePersistence.html">Multiplicative Persistence.</a>
%e A046500 47 -> 28 -> 16 -> 6 has persistence 3.
%t A046500 a[n_]:=Length[NestWhileList[Times@@IntegerDigits[#]&,n,#>9&]]-1; t={}; i=1; Do[While[a[p=Prime[i]]!=n,i++]; AppendTo[t,p],{n,0,9}]; t (* _Jayanta Basu_, Jun 02 2013 *)
%Y A046500 Cf. A003001, A014120.
%K A046500 nonn,base,more,hard,nice
%O A046500 0,1
%A A046500 _Patrick De Geest_, Sep 15 1998
%E A046500 a(10)-a(11) found by _Jud McCranie_