cp's OEIS Frontend

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.

%I A028308 #11 Mar 11 2019 03:56:39
%S A028308 1,6,48,4320,46448640,10835538739200000,
%T A028308 2672817951712314077919313920000000
%N 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.
%C A028308 The next term has 69 digits. - _Charlie Neder_, Mar 09 2019
%H A028308 <a href="http://www.mathpro.com/math/archive/RusMath.txt">Problem 401 here suggested this sequence</a>
%e A028308 Solutions for n=1,2,... are 1; 2 3; 3 2 4; 4 2 3 5; 5 3 2 4 7
%e A028308 Example triangle for a(4):
%e A028308    4    2    3    5
%e A028308      8    6    15
%e A028308        48    90
%e A028308          4320
%e A028308 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 A028308 A less interesting cousin of A028307.
%K A028308 nonn
%O A028308 1,2
%A A028308 _N. J. A. Sloane_
%E A028308 a(7) and example removed from title by _Charlie Neder_, Mar 09 2019