( ( calculated-!n
  =   memo answ
    .   (memo==)
      & ( !arg:0&1
        | !arg:1&0
        | !(memo.):? (!arg.?answ) ?&!answ
        |       (!arg+-1)
              * (calculated-!n$(!arg+-1)+calculated-!n$(!arg+-2))
            : ?answ
          & (!arg.!answ) !(memo.):?(memo.)
          & !answ
        )
  )
& ( counted-!n
  =   p P h H A Z L
    .     !arg:(%?p ?P.?H.?L)
        &   !H
          :   ?A
              (%@?h:~!p)
              (?Z&counted-!n$(!P.!A !Z.!h !L))
      |   !arg:(..?L)
        & 1+!count:?count
        & (!count.!L) !D:?D
        & ~
  )
& out$"Derangements of 1 2 3 4"
& :?D
& 0:?count
& ( counted-!n$(4 3 2 1.4 3 2 1.)
  | out$!D
  )
& ( pad
  =   len w
    .   @(!arg:? [?len)
      & @("       ":? [!len ?w)
      & !w !arg
  )
& :?K
& -1:?N
& out$(str$(N pad$List pad$Calc))
&   whl
  ' ( !N+1:<10:?N
    & (   0:?count
        & :?D
        & counted-!n$(!K.!K.)
      | out$(str$(!N pad$!count pad$(calculated-!n$!N)))
      )
    & !N !K:?K
    )
& out$("!20 =" calculated-!n$20)
& lst$calculated-!n
)