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 A321009 #9 Apr 10 2019 01:25:39 %S A321009 2,4,12,48,240,10,70,560,54,540,5940,71280,9240,129360,19,304,5168, %T A321009 93024,145,29,609,198,0 %N A321009 a(1)=2; thereafter a(n) is obtained by applying Eric Angelini's remove-repeated-digits map, x->A320486(x), to n*a(n-1), stopping when 0 is reached. %D A321009 Eric Angelini, Posting to Sequence Fans Mailing List, Oct 24 2018 %e A321009 a(5)=240, so for a(6) we compute 6*240 = 1440 which becomes 10 = a(6). %Y A321009 Cf. A320485, A320486, A321008. %K A321009 nonn,base,fini,full %O A321009 1,1 %A A321009 _N. J. A. Sloane_, Nov 03 2018