[ Eq(Derivative(x1, t), ((-1)*k1*k2*x1*x2 + 1*k1*k13 + (-1)*k1*k16*x8*x1)/k1),
  Eq(Derivative(x2, t), ((-1)*k1*k2*x1*x2 + (-1)*k1*k6*x9*x2 + 1*k1*k8*x10*x10 + (-1)*k1*k12*x12*x2 + 1*k1*k14*k19 + (-1)*k1*k15*x2)/k1),
  Eq(Derivative(x3, t), (1*k1*k2*x1*x2 + (-1)*k1*k3*x3*x4 + 1*k1*k8*x10*x10)/k1),
  Eq(Derivative(x4, t), ((-1)*k1*k3*x3*x4 + 1*k1*k5*x7*x6 + (-1)*k1*k7*x10*x4 + (-1)*k1*k11*x4*x9)/k1),
  Eq(Derivative(x5, t), (1*k1*k3*x3*x4 + (-1)*k1*k4*x5*x6 + 1*k1*k9*x11*x9)/k1),
  Eq(Derivative(x6, t), ((-1)*k1*k4*x5*x6 + (-1)*k1*k5*x7*x6 + 1*k1*k16*x8*x1)/k1),
  Eq(Derivative(x7, t), (1*k1*k4*x5*x6 + (-1)*k1*k5*x7*x6)/k1),
  Eq(Derivative(x8, t), (1*k1*k4*x5*x6 + 1*k1*k5*x7*x6 + (-1)*k1*k16*x8*x1)/k1),
  Eq(Derivative(x9, t), ((-1)*k1*k6*x9*x2 + (-1)*k1*k9*x11*x9 + (-2)*k1*k10*x9*x9 + (-1)*k1*k11*x4*x9 + 1*k1*k16*x8*x1)/k1),
  Eq(Derivative(x10, t), (1*k1*k6*x9*x2 + (-1)*k1*k7*x10*x4 + (-2)*k1*k8*x10*x10)/k1),
  Eq(Derivative(x11, t), (1*k1*k7*x10*x4 + (-1)*k1*k9*x11*x9 + 1*k1*k12*x12*x2)/k1),
  Eq(Derivative(x12, t), (1*k1*k11*x4*x9 + (-1)*k1*k12*x12*x2)/k1),
  Eq(Derivative(x13, t), 0),
  Eq(Derivative(x14, t), 0),
  Eq(Derivative(x15, t), 0),
  Eq(Derivative(x16, t), 0) ]