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 A306272 #7 Feb 05 2019 21:15:07 %S A306272 0,2,12,78,686,6056,59002,616522,7009264,86023126 %N A306272 Sum of distinct distances between n non-attacking rooks over all n X n chessboards. %C A306272 a(n)/n! gives the expected number of distinct distances of n non-attacking rooks on a random n X n chessboard. %C A306272 n!*A319476(n) <= a(n) <= n!*A320448(n). %Y A306272 Cf. A319476, A320448. %K A306272 nonn,more %O A306272 1,2 %A A306272 _Peter Kagey_, Feb 01 2019