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 A088216 #7 Sep 08 2019 05:27:30 %S A088216 0,324,38831,6773999,1859163031 %N A088216 Smallest nonnegative number not expressible as determinant of an n X n matrix with elements 1..n^2. %H A088216 Hugo Pfoertner, <a href="http://www.randomwalk.de/sequences/a088238.txt">Find all possible values of det(A) for matrix with elements 1..n^2.</a> FORTRAN program. %e A088216 a(2)=0 because the 2 X 2 determinant of a matrix with entries that are permutations of 1,2,3,4 can only assume the values +-2,+-5,+-10. %Y A088216 a(3)=A088214(1), a(4)=A088237(1), a(5)=A088238(1), a(6)=A325900(1). %Y A088216 Cf. A085000, A088215, A088217, A322576. %K A088216 nonn,more,hard %O A088216 2,2 %A A088216 _Hugo Pfoertner_, Sep 23 2003 %E A088216 a(6) from _Hugo Pfoertner_, Sep 07 2019