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 A181512 #7 May 17 2016 07:56:23
%S A181512 1,1,1,1,2,2,1,3,3,6,6,1,4,4,12,12,24,24,1,5,5,5,20,20,20,60,60,120,
%T A181512 120,1,6,6,6,30,30,30,30,120,120,120,360,360,720,720,1,7,7,7,7,42,42,
%U A181512 42,42,42,210,210
%N A181512 Irregular triangle a(n,k) = A181415(n,k) / A036040(n,k).
%C A181512 This is an irregular table related to labeled rooted trees and to Bell numbers.
%C A181512 A181511 contains the same values, without repetition.
%F A181512 sum_{k=1.. A000041(n)} a(n,k) = A181513(n). (Row sums)
%e A181512 1;
%e A181512 1,1;
%e A181512 1,2,2;
%e A181512 1,3,3,6,6;
%e A181512 1,4,4,12,12,24,24;
%e A181512 1,5,5,5,20,20,20,60,60,120,120;
%e A181512 1,6,6,6,30,30,30,30,120,120,120,360,360,720,720;
%Y A181512 Cf. A181511, A181513 (row sums).
%K A181512 nonn,tabf
%O A181512 1,5
%A A181512 _Alford Arnold_, Oct 26 2010