[解析]
解:(1)输入a的值为﹣1,输出结果为:
[(﹣1)2﹣2]×(﹣3)+4
=(1﹣2)×(﹣3)+4
=(﹣1)×(﹣3)+4
=3+4
=7;
故答案为:7;
(2)当x<1时,2x+6=0,
解得:x=﹣3;
当x≥1时,8x=0,
解得:x=0,不符合题意,舍去;
故答案为:﹣3;
(3)当A输入自然数7,B输入自然数6,则m=7,n=6,
根据性质③:
k=C(7,6)
=C(7,6﹣1)+2
=C(7,5)+2
=[C(7,5﹣1)+2]+2
=C(7,4)+2+2
=[C(7,4﹣1)+2]+2+2
=C(7,3)+2+2+2
=[C(7,3﹣1)+2]+2+2+2
=C(7,2)+2+2+2+2
=[C(7,2﹣1)+2]+8
=[C(7,1)+2]+8
=C(7,1)+10,
根据性质②:
k=C(7,1)+10
=2×[C(6,1)]+10
=2×2×[C(5,1)]+10
=2×2×2×[C(4,1)]+10
=2×2×2×2×[C(3,1)]+10
=16×2×[C(2,1)]+10
=32×2×[C(1,1)]+10,
根据性质①:
k=64×[C(1,1)]+10
=64×1+10
=64+10
=74,
综上所述,k的值为74.