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A181512 Irregular triangle a(n,k) = A181415(n,k) / A036040(n,k). 2

%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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Last modified March 29 10:44 EDT 2024. Contains 371268 sequences. (Running on oeis4.)