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 A247902 #9 Jun 02 2025 10:15:52 %S A247902 90,18,36,18,18,54,36,90,18,72,18,18,18,36,18,54,18,90,18,18,18,18,18, %T A247902 36,18,36,18,18,18,36,90,36,18,18,18,72,18,54,18,18,18,18,54,36,18,18, %U A247902 18,18,18,54,36,36,18,36,36,18,18,54,18,54,36,18,18,18,18,18,54,18,18,72,18,54,36,36,18,36,36,18,18,18,18 %N A247902 First differences of A247683. %C A247902 All terms have digital root equal to 9. %H A247902 Odimar Fabeny, <a href="/A247902/b247902.txt">Table of n, a(n) for n = 1..10000</a> %Y A247902 Cf. A247683. %K A247902 nonn,easy %O A247902 1,1 %A A247902 _Odimar Fabeny_, Sep 26 2014