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 A319283 #9 Sep 18 2018 02:41:31 %S A319283 1,2,3,6,17,54,153,552,2057,8394,35539,166926,856189,4674890,27358553, %T A319283 171129072,1141190303,8017021932,59365844491,461939618824 %N A319283 Number of nodes of the backtrack tree for the n queens problem. %D A319283 D. E. Knuth, The Art of Computer Programming, Volume 4, Pre-fascicle 5B, Introduction to Backtracking, 7.2.2. Backtrack programming. 2018. %Y A319283 Row sums of A319284. %Y A319283 Cf. A000170. %K A319283 nonn,more %O A319283 0,2 %A A319283 _Peter Luschny_, Sep 16 2018