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, 6, 48, 4320, 46448640, 10835538739200000, 2672817951712314077919313920000000

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn

Comments

The next term has 69 digits. - Charlie Neder, Mar 09 2019

Examples

			Solutions for n=1,2,... are 1; 2 3; 3 2 4; 4 2 3 5; 5 3 2 4 7
Example triangle for a(4):
   4    2    3    5
     8    6    15
       48    90
         4320
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
		

Links

• Problem 401 here suggested this sequence

Crossrefs

A less interesting cousin of A028307.

Extensions

a(7) and example removed from title by Charlie Neder, Mar 09 2019