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 A247898 #11 Jun 02 2025 10:15:29 %S A247898 36,36,54,72,18,36,18,36,36,36,18,36,36,18,18,36,36,54,18,18,90,36,54, %T A247898 18,18,18,36,18,54,18,36,36,18,18,36,36,18,36,36,18,54,18,72,18,36,54, %U A247898 18,18,36,18,90,18,36,36,18,18,18,18,18,72,18,36,18,36,18,18,18,18,18,18,36,18,18,18,54,18,18,18,18,18,18 %N A247898 First differences of A247678. %C A247898 All terms have digital root equal to 9. %H A247898 Odimar Fabeny, <a href="/A247898/b247898.txt">Table of n, a(n) for n = 1..10000</a> %t A247898 Differences[Select[Range[13,3000,18],CompositeQ]] (* _Harvey P. Dale_, Aug 21 2024 *) %Y A247898 Cf. A247678. %K A247898 nonn,easy %O A247898 1,1 %A A247898 _Odimar Fabeny_, Sep 26 2014