Experiment with the exp_factor params.

def attention_lm_ae_extended():
  """Experiment with the exp_factor params."""
  hparams = attention_lm_moe_base_long_seq()
  hparams.attention_layers = "eeee"
  hparams.attention_local = True
  # hparams.factored_logits=1  # Necessary when the number of expert grow bigger
  hparams.attention_moe_k = 2
  hparams.attention_exp_factor = 4
  # hparams.attention_exp_inputdim = 128

  hparams.layer_preprocess_sequence = "n"
  hparams.layer_postprocess_sequence = "da"
  return hparams