YES
TRS:
 {           sqr(0()) -> 0(),
             sqr(s()) -> s(),
             terms(N) -> cons(recip(sqr(N))),
             dbl(0()) -> 0(),
             dbl(s()) -> s(),
          add(0(), X) -> X,
          add(s(), Y) -> s(),
        first(0(), X) -> nil(),
  first(s(), cons(Y)) -> cons(Y)}
 RUF:
  Strict:
   {sqr(0()) -> 0(),
    sqr(s()) -> s()}
  Weak:
   {}
  RUF:
   Strict:
    {}
   Weak:
    {}
   Qed