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 A057668 #9 Feb 16 2025 08:32:43 %S A057668 1,988,549102,226064280,76785889587,22762819040676,6092115565691584, %T A057668 1505097773271664000,348617485585838373333,76564317282173987801964, %U A057668 16080209472530744351164146,3250906483045575317042337960,635954979082842132795003641239 %N A057668 Number of minimal 7-covers of a labeled n-set. %H A057668 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/MinimalCover.html">Minimal cover</a> %F A057668 a(n) = (1/7!) * (127^n - 7 * 126^n + 21 * 125^n - 35 * 124^n + 35 * 123^n - 21 * 122^n + 7 * 121^n - 120^n). %F A057668 G.f.: x^7 / ((120*x-1)*(121*x-1)*(122*x-1)*(123*x-1)*(124*x-1)*(125*x-1)*(126*x-1)*(127*x-1)). - _Colin Barker_, Jul 11 2013 %Y A057668 Cf. A000392, A003468, A016111, A046166-A046169, A005783-A005786, A055066 (unlabeled case). %K A057668 easy,nonn %O A057668 7,2 %A A057668 _Vladeta Jovovic_, Oct 16 2000 %E A057668 Additional term from _Colin Barker_, Jul 11 2013