The nullary operators in Maple are:

$1\;$$2\;$$3$

$1$

$2$

$3$

$\%,\mathrm{`\%\%`},\mathrm{`\%\%\%`}$

$3,2,1$

F := proc( n ) 1; 2; to n do % + % * % / %% end do end proc;

$F≔\mathbf{proc}\left(n\right)1\;2\;\mathbf{to}n\mathbf{do}\%\+\%\*\%\/\mathrm{\%\%}\mathbf{end\; do}\mathbf{end\; proc}$

$F\left(8\right)$

$3628800$