code: def _limit_seq(expr, n, trials):
      from sympy.concrete.summations import Sum
  
      for i in range(trials):
          if not expr.has(Sum):
              result = _limit_inf(expr, n)
              if result is not None:
                  return result
  
          num, den = expr.as_numer_denom()
          if not den.has(n) or not num.has(n):
              result = _limit_inf(expr.doit(), n)
              if result is not None:
                  return result
              return None
  
          num, den = (
              difference_delta(t.expand(), n) for t in [num, den]
          )
          expr = (num / den).gammasimp()
  
          if not expr.has(Sum):
              result = _limit_inf(expr, n)
              if result is not None:
                  return result
  
          num, den = expr.as_numer_denom()
  
          num = dominant(num, n)
          if num is None:
              return None
  
          den = dominant(den, n)
          if den is None:
              return None
  
          expr = (num / den).gammasimp()
  
file_path: sympy/sympy/series/limitseq.py
imports: from sympy.calculus.accumulationbounds import AccumulationBounds
  from sympy.core.add import Add
  from sympy.core.function import PoleError
  from sympy.core.power import Pow
  from sympy.core.singleton import S
  from sympy.core.symbol import Dummy
  from sympy.core.sympify import sympify
  from sympy.functions.combinatorial.numbers import fibonacci
  from sympy.functions.combinatorial.factorials import factorial, subfactorial
  from sympy.functions.special.gamma_functions import gamma
  from sympy.functions.elementary.complexes import Abs
  from sympy.functions.elementary.miscellaneous import Max, Min
  from sympy.functions.elementary.trigonometric import cos, sin
  from sympy.series.limits import Limit
label_desc: Use image node_id 4 for calling a global function with example usage: _limit_seq(expr, n, trials) and returns: None, None, None, result, result, result