YES
O(n^2)
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)
 }
 Natural interpretation:
  Strict:
   {
               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)
   }
  Weak:
   {}
  Interpretation class: deltarestricted
  [first](delta, X1, X0) = + 1*X0 + 1*X1 + 1 + 0*X0*delta + 0*X1*delta + 1*delta
  [nil](delta) = + 0 + 0*delta
  [add](delta, X1, X0) = + 1*X0 + 0*X1 + 1 + 0*X0*delta + 1*X1*delta + 1*delta
  [dbl](delta, X0) = + 1*X0 + 0 + 0*X0*delta + 1*delta
  [s](delta) = + 1 + 0*delta
  [0](delta) = + 1 + 1*delta
  [terms](delta, X0) = + 0*X0 + 1 + 1*X0*delta + 1*delta
  [sqr](delta, X0) = + 0*X0 + 1 + 1*X0*delta + 0*delta
  [recip](delta, X0) = + 1*X0 + 0 + 0*X0*delta + 0*delta
  [cons](delta, X0) = + 1*X0 + 0 + 0*X0*delta + 0*delta
  first_tau_1(delta) = delta/(1 + 0 * delta)first_tau_2(delta) = delta/(1 + 0 * delta)
  
  add_tau_1(delta) = delta/(0 + 1 * delta)add_tau_2(delta) = delta/(1 + 0 * delta)
  dbl_tau_1(delta) = delta/(1 + 0 * delta)
  
  
  terms_tau_1(delta) = delta/(0 + 1 * delta)
  sqr_tau_1(delta) = delta/(0 + 1 * delta)
  recip_tau_1(delta) = delta/(1 + 0 * delta)
  cons_tau_1(delta) = delta/(1 + 0 * delta)
  
  Qed