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 A130851 #13 Jan 25 2020 00:48:25 %S A130851 1,1,2,5,5,6,6,6,8,2,2,7,4,4,0,0,0,6,6,6,3,3,3,0,0,0,8,2,2,4,1,1,3,3, %T A130851 3,1,7,7,2,5,5,0,0,0,0,0,0,0,0,0,0,0,0,6,6,6,3,3,3,0,0,0,3,3,3,6,6,6, %U A130851 0,0,0,0,0,0,0,0,0,0,0,0,8,2,2,4,1,1,3,3,3,7,4,4,5,8,8,0,0,0,3,3,3,6,6,6,0 %N A130851 Catalan numbers A000108(n) modulo 9. %F A130851 a(n) = A000108(n) mod 9. - _Philippe Deléham_, Apr 28 2009 %t A130851 Mod[CatalanNumber[Range[0,120]],9] (* _Harvey P. Dale_, Feb 20 2018 *) %Y A130851 Cf. A000108, A010888, A130856. %K A130851 nonn,easy,base %O A130851 0,3 %A A130851 _N. J. A. Sloane_, Aug 21 2007 %E A130851 Name corrected by _Nathaniel Johnston_, May 05 2011