print my 1st page on last, 2nd page with 2nd last how ?

trying to print a3 designs on 12X18inch paper but i need to print my first page on last, second page with 2nd last etc

1,50,2,49,3,48,4,47,5,46,6,45,7,44,8,43,9,42,10,41,11,40,12,39,13,38,14,37,15,36,16,35,17,34,18,33,19,32,20,31,21,30,22,29,23,28,24,27,25,26

i usually make a series like the above to print but all the time i put these numbers manually to print my first page on last, second on second last, third on third last, etc.

please help  to create this kind of series for my printing with macro