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 A247899 #9 Jun 02 2025 10:15:36 %S A247899 90,18,18,54,72,18,18,18,36,18,18,72,54,36,36,18,36,72,18,36,54,54,18, %T A247899 18,54,18,18,18,36,36,18,36,36,36,54,18,18,18,36,18,18,36,18,54,18,18, %U A247899 90,18,18,36,18,18,18,18,18,18,18,72,18,18,54,18,18,54,18,36,18,18,36,18,36,18,18,54,54,36,18,18,18,18,18 %N A247899 First differences of A247679. %C A247899 All terms have digital root equal to 9. %H A247899 Odimar Fabeny, <a href="/A247899/b247899.txt">Table of n, a(n) for n = 1..10000</a> %Y A247899 Cf. A247679. %K A247899 nonn,easy %O A247899 1,1 %A A247899 _Odimar Fabeny_, Sep 26 2014