1x2x3x4+1=25=5²=(1²+3×1+1)²2x3x4x5x6+1=121=11²=(2²+3×2+1)²3x4x5x6x7+1=361=19²=(3²+3×3+1)²所以四个连续自然数的乘积再加上1,是个完全平方数所以a(a+1)(a+2)(a...