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 A000519 #25 Apr 03 2020 11:32:00 %S A000519 1,2,3,5,7,18,43,313,7525,846992,324127859,403254094631, %T A000519 1555631972009429,19731915624463099552,791773335030637885025287, %U A000519 107432353216118868234728540267,47049030539260648478475949282317451,71364337698829887974206671525372672234854 %N A000519 Number of equivalence classes of nonzero regular 0-1 matrices of order n. %C A000519 Previous name was: Number of different row sums among Latin squares of order n. %C A000519 A regular 0-1 matrix has all row sums and column sums equal. Equivalence is defined by independently permuting rows and columns (but not by transposing). - _Brendan McKay_, Nov 18 2015 %H A000519 <a href="/index/La#Latin">Index entries for sequences related to Latin squares and rectangles</a> %F A000519 a(n) = A333681(n-1). - _Andrew Howroyd_, Apr 03 2020 %e A000519 For n = 4, representatives of the a(4) = 5 classes are %e A000519 [1 0 0 0] [1 1 0 0] [1 1 0 0] [1 1 1 0] [1 1 1 1] %e A000519 [0 1 0 0] [1 1 0 0] [0 1 1 0] [1 1 0 1] [1 1 1 1] %e A000519 [0 0 1 0] [0 0 1 1] [0 0 1 1] [1 0 1 1] [1 1 1 1] %e A000519 [0 0 0 1] [0 0 1 1] [1 0 0 1] [0 1 1 1] [1 1 1 1]. %e A000519 G.f. = x + 2*x^2 + 3*x^3 + 5*x^4 + 7*x^5 + 18*x^6 + 43*x^7 + 313*x^8 + 7525*x^9 + ... %Y A000519 One less than the row sums of A133687. %Y A000519 Cf. A333681. %K A000519 nonn %O A000519 1,2 %A A000519 Eric Rogoyski %E A000519 Description changed, after discussion with Andrew Howroyd, by _Brendan McKay_, Nov 18 2015 %E A000519 Terms a(12) and beyond from _Andrew Howroyd_, Apr 03 2020