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A028308 Form a triangle with n numbers in top row; all other numbers are the product of their parents. The numbers must be positive and distinct and the final number is to be minimized. 1

%I

%S 1,6,48,4320,46448640,10835538739200000,

%T 2672817951712314077919313920000000

%N Form a triangle with n numbers in top row; all other numbers are the product of their parents. The numbers must be positive and distinct and the final number is to be minimized.

%C The next term has 69 digits. - _Charlie Neder_, Mar 09 2019

%H <a href="http://www.mathpro.com/math/archive/RusMath.txt">Problem 401 here suggested this sequence</a>

%e Solutions for n=1,2,... are 1; 2 3; 3 2 4; 4 2 3 5; 5 3 2 4 7

%e Example triangle for a(4):

%e 4 2 3 5

%e 8 6 15

%e 48 90

%e 4320

%e Some solutions for a(6) and a(7) are (7,4,3,2,5,8) and (9,7,4,2,3,5,10), and others can be created by interchanging opposite numbers (e.g., swapping 5 and 7 in the second set). - _Charlie Neder_, Mar 09 2019

%Y A less interesting cousin of A028307.

%K nonn

%O 1,2

%A _N. J. A. Sloane_

%E a(7) and example removed from title by _Charlie Neder_, Mar 09 2019

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Last modified September 19 22:06 EDT 2021. Contains 347576 sequences. (Running on oeis4.)