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 A322576 #46 Aug 14 2021 18:55:34 %S A322576 0,1,9,139,2111,40021,942937,27003797 %N A322576 Least nonnegative integer that cannot be expressed as the determinant of an n X n matrix whose entries are a permutation of the multiset {1^n, ..., n^n}. %e A322576 a(1) = 0 because det[1] = 1. %e A322576 a(2) = 1 because det[1,1; 2,2] = 0 and det[2,1; 1,2] = 3 are the only determinant values >= 0 that can be made by permuting the matrix entries {1,1, 2,2}. %e A322576 a(3) = 9, because it is the first missing value in the list of A309799(3) = 13 determinant values corresponding to {1,1,1, 2,2,2, 3,3,3}: 0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 13, 15, 18. %Y A322576 Cf. A088216, A301371, A309258, A309799, A327281. %K A322576 nonn,more,hard %O A322576 1,3 %A A322576 _Hugo Pfoertner_, Aug 29 2019