execl joining columns

COLUMN33 

Maybe you do not have Excel 365?  With old Excel, a starting point might be

= INDEX(
    array, 
    1+MOD({1;2;3;4;5;6}-1,3), 
    1+QUOTIENT({1;2;3;4;5;6}-1,3)
  )

but either it would need to be committed with Ctrl/Shift/Enter or placed within a defined name, where array formulas have always worked correctly.  I am glad to say I no longer need to use these horrible old systems!