const MAX = 12;
var super=Data(), pos, cnt;  // global state, ick

fcn fact_sum(n){ // -->1! + 2! + ... + n!
   [1..n].reduce(fcn(s,n){ s + [2..n].reduce('*,1) },0)
}

fcn r(n){
   if (not n) return(0);

   c := super[pos - n];
   if (not (cnt[n]-=1)){
      cnt[n] = n;
      if (not r(n-1)) return(0);
   }
   super[pos] = c; pos+=1;
   1
}

fcn superperm(n){
   pos = n;
   len := fact_sum(n);
   super.fill(0,len);  // this is pretty close to recalloc()

   cnt = (n+1).pump(List()); //-->(0,1,2,3,..n)
   foreach i in (n){ super[i] = i + 0x31; } //-->"1" ... "123456789:;"
   while (r(n)){}
}

foreach n in (MAX){
   superperm(n);
   print("superperm(%2d) len = %d".fmt(n,super.len()));
   // uncomment next line to see the string itself
   //print(": %s".fmt(super.text));
   println();
}