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 A247897 #10 Jun 02 2025 10:15:23 %S A247897 54,36,54,36,54,36,36,36,18,72,18,18,18,54,18,72,18,18,18,18,18,18,72, %T A247897 18,72,36,36,18,18,54,18,54,36,18,18,54,18,36,18,18,54,36,36,36,18,36, %U A247897 18,36,18,36,18,18,18,36,36,18,36,18,18,36,18,36,72,18,36,18,36,36,18,36,54,18,18,90,18,54,18,18,36,36,72 %N A247897 First differences of A247676. %C A247897 All terms have digital root equal to 9. %H A247897 Odimar Fabeny, <a href="/A247897/b247897.txt">Table of n, a(n) for n = 1..10000</a> %Y A247897 Cf. A247676. %K A247897 nonn,easy %O A247897 1,1 %A A247897 _Odimar Fabeny_, Sep 26 2014