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 A121106 #8 Nov 19 2021 18:05:36 %S A121106 6788,2688,768,336,54,20,0 %N A121106 Trajectory of 6788 under "x -> product of digits of x" map. %C A121106 This is the smallest number of persistence 6 (cf. A003001). %H A121106 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. %t A121106 NestList[Times@@IntegerDigits[#]&,6788,6] (* _Harvey P. Dale_, Nov 19 2021 *) %Y A121106 Cf. A003001. %K A121106 nonn,fini,full,base %O A121106 1,1 %A A121106 _N. J. A. Sloane_, Aug 12 2006 %E A121106 Edited by _Charles R Greathouse IV_, Aug 06 2010