∑m(n-1)anx=∑(n+2)n+1)a n+2 n=1 将y,y3,y"带入y"-xy'-y=0, E E(n+2)(+1)am2*xEna, 2a,"=0, =0 0 n ∑(n+2)n+1)un2-(n+1anx"≡0 n+2 = 0,1,2, n+ 2 上页2 1 ( 1) −  =  =  − n n y n n an x 将 y, y , y 带入 y − xy − y = 0, ( 2)( 1) , 0 2 n n  n n a n x  = = + + + 0, 0 −  =  = n n a n x 1 0 −  = −  n n x nan x n n  n n an x  = + + + 0 2 ( 2)( 1) [( 2)( 1) ( 1) ] 0, 0  + + 2 − +   = + n n n n a n n a n x , 2 2 + + = n a a n n n = 0,1,2, 