Practice 4(I) recently

 positive number is =          23
           I       Y(I)
           1    -2.62536426E+15
           2    -3.01916895E+16
           3    -3.47204435E+17
           4    -3.99285091E+18
           5    -4.59177870E+19
           6    -5.28054551E+20
           7    -6.07262728E+21
           8    -6.98352117E+22
           9    -8.03104944E+23
          10    -9.23570714E+24
          11    -1.06210634E+26
          12    -1.22142231E+27
          13    -1.40463556E+28
          14    -1.61533079E+29
          15    -1.85763043E+30
          16    -2.13627492E+31
          17    -2.45671619E+32
          18    -2.82522366E+33
          19    -3.24900706E+34
          20    -3.73635815E+35
          21    -4.29681168E+36
          22    -4.94133348E+37
          23          -Infinity
          24          -Infinity
          25          -Infinity
          26          -Infinity
          27          -Infinity
          28          -Infinity
          29          -Infinity
          30          -Infinity