>>370-371

もう1つ...

・例3
 a_1 = 0.66763055
 a_2 = 0.66280835
 a_k = a_2・r^(k-2)  (k>2)
 r ={(7+4√3)^(1/3)+(7-4√3)^(1/3)- 1}/4 = 0.455410041101
   (4r^3 +3rr -1 = 0 の実根)
のとき
 M =(2/3)√{(1+r)(1-r^3)/3}= 0.4418722310911 < 0.48