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 A276894 #10 Jul 18 2017 08:17:41
%S A276894 1,1,3,13,75,466,3272,26032,232820,2304600,25003176,295139034,
%T A276894 3767545662,51729553992,760326663792,11913105530016,198246166468224,
%U A276894 3492246172917240,64928731038925800,1270685662509505560,26112819120798942120,562241528313838756560
%N A276894 Number of ordered set partitions of [n] such that for each block b the smallest integer interval containing b has at most four elements.
%H A276894 Alois P. Heinz, <a href="/A276894/b276894.txt">Table of n, a(n) for n = 0..449</a>
%F A276894 a(n) ~ exp(3) * n!. - _Vaclav Kotesovec_, Sep 22 2016
%t A276894 b[n_, m_, l_List] := b[n, m, l] = If[n == 0, m!, Sum[b[n - 1, Max[m, j], Append[ReplacePart[l, 1 -> Nothing], If[j <= m, 0, j]]], {j, Append[l, m + 1] ~Complement~ {0}}]]; a[n_] := b[n, 0, {0, 0, 0}]; Table[a[n], {n, 0, 21}] (* _Jean-François Alcover_, Jul 18 2017, after _Alois P. Heinz_ *)
%Y A276894 Column k=4 of A276890.
%Y A276894 Cf. A276720.
%K A276894 nonn
%O A276894 0,3
%A A276894 _Alois P. Heinz_, Sep 21 2016