21/01/21 13:04:29.34 IkgM63pN.net
前>>449
>>483
(a,b,c)=(1,29,30).(1,28,29),(1,27,28),(1,26,27),……(1,2,3)
(2,28,30),(2,27,29),……(2,3,5),(2,1,3)
(3,27,30),(3,26,29),……(3,4,7),(3,1,4),(3,2,5)
……
(11,19,30),(11,18,29),……(11,12,23),(11,1,12),(11,2,13),……(11,10,21)
(12,18,30),(12,17,29),……(12,13,25),(12,1,13),(12,2,14),……(12,11,23)
……
(23,7,30),(23,6,29),……(23,
(24,6,30),(24,5,29),……(24,
(25,5,30),(25,4,29),(25,3,28),(25,2,27),(25,1,26)
(26,4,30),(26,3,29),(26,2,28),(26,1,27)
(27,3,30),(27,2,29),(27,1,28)
(28,2,30),(28,1,29)
(29,1,30)
x=28+27+26+……+18+17+……+7+6+5+4+3+2+1
=(28+1)×(28/2)
=14×29
=290+116
=406