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 A368511 #10 Dec 28 2023 11:31:53
%S A368511 1,1,2,6,66,450,3690,35280,385560,6717480,96117000,1512819000,
%T A368511 25975395600,483169486800,9678799930800,207733600074000,
%U A368511 5243385642495000,128458209887007000,3332234177825553000,91241046790816923000,2629791992312269785000,79586945507310941700000
%N A368511 Number of ordered partitions of an n-set into blocks of size <= sqrt(n).
%F A368511 a(n) = n! * [x^n] 1 / (1 - Sum_{1 <= j <= sqrt(n)} x^j / j!).
%t A368511 Table[n! SeriesCoefficient[1/(1 - Sum[x^j/j!, {j, 1, Floor[Sqrt[n]]}]), {x, 0, n}], {n, 0, 21}]
%Y A368511 Cf. A000670, A368502, A368512.
%K A368511 nonn
%O A368511 0,3
%A A368511 _Ilya Gutkovskiy_, Dec 28 2023