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