Page 54 - Foundations Of Differential Calculus
P. 54

2. On the Use of Differences in the Theory of Series  37
        where C is the constant we obtain by letting S.X vanish when we let x =0.
        It follows that we can express the partial sum of the series of powers, that
                                                        n
        is, the series for which the general term has the form x .Welet


                                             n
                                                      n
                                    n
                                        n
                         S.X = 1+2 +3 +4 + ··· + x .
        Then


                  1   n+1  1  n   1   n  n−1   1 n (n − 1) (n − 2)  n−3
            n
         S.x =       x   + x +     ·    x    −   ·               x
                n +1       2      2 2 · 3      6     2 · 3 · 4 · 5
                 1 n (n − 1) (n − 2) (n − 3) (n − 4)  n−5
               +   ·                            x
                 6           2 · 3 ··· 6 · 7
                  3  n (n − 1) ··· (n − 6)  n−7
               −    ·                 x
                 10      2 · 3 ··· 8 · 9
                 5 n (n − 1) ··· (n − 8)  n−9  691 n (n − 1) ··· (n − 10)  n−11
               +   ·                 x    −     ·                  x
                 6     2 · 3 ··· 10 · 11    210     2 · 3 ··· 12 · 13
                 35 n (n − 1) ··· (n − 12)  n−13
               +    ·                  x
                  2     2 · 3 ··· 14 · 15
                 3617 n (n − 1) ··· (n − 14)  n−15
               −      ·                  x
                  30      2 · 3 ··· 16 · 17
                 43867 n (n − 1) ··· (n − 16)  n−17
               +       ·                  x
                   42      2 · 3 ··· 18 · 19
                 1222277 n (n − 1) ··· (n − 18)  n−19
               −         ·                  x
                   110       2 · 3 ··· 20 · 21
                 854513 n (n − 1) ··· (n − 20)  n−21
               +        ·                  x
                    6       2 · 3 ··· 22 · 23
                 1181820455 n (n − 1) ··· (n − 22)  n−23
               −            ·                  x
                     546        2 · 3 ··· 24 · 25
                 76977927 n (n − 1) ··· (n − 24)  n−25
               +          ·                  x
                     2        2 · 3 ··· 26 · 27
                 23749461029 n (n − 1) ··· (n − 26)  n−27
               −             ·                  x     ,
                      30         2 · 3 ··· 28 · 29



        and so forth.
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