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A354697 a(n) is the least integer that can be written in two or more ways as the product of the integers in two subsets of its A070824(a(n)) nontrivial divisors, each of size n and with empty intersection. 3

%I #40 May 14 2024 13:40:52

%S 12,120,720,10080,110880,1814400,26611200,518918400,10378368000,

%T 261534873600,5928123801600,168951528345600,4505374089216000,

%U 152056375511040000,4663062182338560000,167870238564188160000,6463004184721244160000,249902828475888107520000,10495918795987300515840000

%N a(n) is the least integer that can be written in two or more ways as the product of the integers in two subsets of its A070824(a(n)) nontrivial divisors, each of size n and with empty intersection.

%C a(6) <= 110880 = 2*3*6*10*14*22 = 4*5*7*8*9*11.

%H Zhao Hui Du, <a href="/A354697/b354697.txt">Table of n, a(n) for n = 2..25</a>

%F A070824(a(n)) >= 2*n.

%e a(2) = 12 = 2*6 = 3*4,

%e a(3) = 120 = 2*3*20 = 4*5*6,

%e a(4) = 720 = 2*4*9*10 = 3*5*6*8,

%e a(5) = 10080 = 2*3*6*10*28 = 4*5*7*8*9.

%e a(6) = 110880 = 2*3*6*10*14*22 = 4*5*7*8*9*11.

%e a(7) = 1814400 = 2*3*4*14*15*18*20 = 5*6*7*8*9*10*12.

%Y Cf. A002182, A025487, A354457.

%K nonn,hard

%O 2,1

%A _Hugo Pfoertner_, Jun 03 2022

%E a(6) confirmed by and a(7)-a(13) from _David A. Corneth_, Jun 04 2022

%E a(14) onwards from _Zhao Hui Du_, May 12 2024

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Last modified June 27 20:20 EDT 2024. Contains 373753 sequences. (Running on oeis4.)