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 A006621 M4776 #20 Dec 26 2021 18:26:33
%S A006621 11,17,23,30,38,46,55,65,75,87
%N A006621 Zarankiewicz's problem k_3(n,n+1).
%C A006621 a(n) is the least k such that every n X (n+1) {0,1}-matrix with k ones contains an all ones 3 X 3 submatrix. - _Sean A. Irvine_, May 18 2017
%D A006621 N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
%H A006621 R. K. Guy, <a href="http://dx.doi.org/10.1007/BFb0060112">A many-facetted problem of Zarankiewicz</a>, Lect. Notes Math. 110 (1969), 129-148.
%Y A006621 Cf. A001198 (k_3(n)), A006620 (k_2(n,n+1)), A006626 (k_4(n,n+1)).
%K A006621 nonn,more
%O A006621 3,1
%A A006621 _N. J. A. Sloane_
%E A006621 a(10)-a(12) from _Andrew Howroyd_, Dec 26 2021