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 A007471 M4597 #13 Dec 26 2021 21:40:02 %S A007471 1,9,9,3,9,9,3,9,9,1,18,9,9,9,9,9,9,9,6,9,18,6,9,9,6,9,9,4,9,9,12,18, %T A007471 18,3,9,9,3,9,9,3,18,18,12,18,9,5,9,9,9,9,18,6,18,18,2,9,9,9,9,9,12,0, %U A007471 0,5,0,18,3,9,9,3,18,18,7,27,0,12,18 %N A007471 Sum of digits of n a(n) is n ( = A003634/n), or 0 if no such number exists. %D A007471 J. H. Conway, personal communication. %D A007471 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). %K A007471 nonn,base %O A007471 1,2 %A A007471 _N. J. A. Sloane_ %E A007471 Zeros inserted for consistency with A003634 by _Sean A. Irvine_, Jan 04 2018