[ temp put 1 unrot
    [ dup while
      dup 1 & if
        [ unrot tuck *
          temp share mod
          swap rot ]
      1 >>
      swap dup *
      temp share mod
      swap again ]
    2drop temp release ] is **mod ( n n n --> n )

 2988348162058574136915891421498819466320163312926952423791023078876139
 2351399303373464486466122544523690094744975233415544072992656881240319
 10 40 ** **mod echo