{ diff(x1, t) = ((-1)*k1*x1*x2 + 1*k2*x3 + 1*k10*x10 + 1*k13*x9*x12 + 1*k38*x33)/k40,
  diff(x2, t) = ((-1)*k1*x1*x2 + 1*k2*x3 + 1*k7*x7 + (-1)*k8*x2*x8 + (-1)*k34*x2*x20 + 1*k35*x28*x31)/k40,
  diff(x3, t) = (1*k1*x1*x2 + (-1)*k2*x3 + (-1)*k3*x3 + 1*k4*x4*k41)/k40,
  diff(x4, t) = (1*k3*x3 + (-1)*k4*x4*k41 + (-1)*k5*x4*k42 + 1*k6*x7)/k40,
  diff(x5, t) = 0,
  diff(x6, t) = 0,
  diff(x7, t) = (1*k5*x4*k42 + (-1)*k6*x7 + (-1)*k7*x7 + 1*k8*x2*x8)/k40,
  diff(x8, t) = (1*k7*x7 + (-1)*k8*x2*x8 + (-1)*k9*x8*x9 + (-1)*k11*x8*x11 + (-1)*k37*x8*x32)/k40,
  diff(x9, t) = ((-1)*k9*x8*x9 + 1*k10*x10 + (-1)*k36*x9*x20 + 1*k39*x32)/k40,
  diff(x10, t) = (1*k9*x8*x9 + (-1)*k10*x10)/k40,
  diff(x11, t) = ((-1)*k11*x8*x11 + 1*k13*x9*x12)/k40,
  diff(x12, t) = (1*k11*x8*x11 + (-1)*k13*x9*x12)/k40,
  diff(x13, t) = 0,
  diff(x14, t) = (1*k12*x12*k43 + (-1)*k14*x14*x15 + (-1)*k15*x14*x16 + (-1)*k16*x14*x17 + (-1)*k17*x14*x18 + 1*k18*x19 + 1*k19*x18 + 1*k20*x17 + 1*k21*x16 + 2*k23*x21 + (-1)*k27*x14*x25 + 1*k28*x26 + (-1)*k31*x14*x29 + 1*k32*x30)/k40,
  diff(x15, t) = ((-1)*k14*x14*x15 + 1*k21*x16 + 1*k25*x23*(x23 - 1)/2)/k40,
  diff(x16, t) = (1*k14*x14*x15 + (-1)*k15*x14*x16 + 1*k20*x17 + (-1)*k21*x16)/k40,
  diff(x17, t) = (1*k15*x14*x16 + (-1)*k16*x14*x17 + 1*k19*x18 + (-1)*k20*x17)/k40,
  diff(x18, t) = (1*k16*x14*x17 + (-1)*k17*x14*x18 + 1*k18*x19 + (-1)*k19*x18)/k40,
  diff(x19, t) = (1*k17*x14*x18 + (-1)*k18*x19 + (-1)*k22*x19)/k40,
  diff(x20, t) = (2*k22*x19 + (-1)*k24*x20*x22)/k40,
  diff(x21, t) = (2*k22*x19 + (-1)*k23*x21)/k40,
  diff(x22, t) = (1*k23*x21 + (-1)*k24*x20*x22)/k40,
  diff(x23, t) = (1*k24*x20*x22 + (-2)*k25*x23*(x23 - 1)/2)/k40,
  diff(x24, t) = ((-1)*k26*x20*x24 + 1*k30*x25*x28)/k40,
  diff(x25, t) = (1*k26*x20*x24 + (-1)*k27*x14*x25 + 1*k28*x26 + 1*k29*x26 + (-1)*k30*x25*x28)/k40,
  diff(x26, t) = (1*k27*x14*x25 + (-1)*k28*x26 + (-1)*k29*x26)/k40,
  diff(x27, t) = (1*k29*x26 + 1*k33*x30)/k40,
  diff(x28, t) = 0/k40,
  diff(x29, t) = ((-1)*k31*x14*x29 + 1*k32*x30 + 1*k33*x30)/k40,
  diff(x30, t) = (1*k31*x14*x29 + (-1)*k32*x30 + (-1)*k33*x30)/k40,
  diff(x31, t) = (1*k34*x2*x20 + (-1)*k35*x28*x31)/k40,
  diff(x32, t) = (1*k36*x9*x20 + (-1)*k37*x8*x32 + 1*k38*x33 + (-1)*k39*x32)/k40,
  diff(x33, t) = (1*k37*x8*x32 + (-1)*k38*x33)/k40 }