็ฌฌ4ๅ~็ฌฌ7ๅใฏ,ใใใใ 3ๅใ้ธๆใ, ่งฃ็ญใใชใใใ
็ฌฌ4ๅ (้ธๆๅ้ก) (้
็น 16)
M
[1] ็ญๅทฎๆฐๅ{an} ใฏ, a2=5, ฮฑ5 = 14 ใๆบใใใฆใใใ
ๅ้
ฮฑ ใฏ
ใข ใงใใ,ๅ
ฌๅทฎใฏ
ใค
ใงใใใใ, ๆฐๅ {a} ใฎไธ่ฌ้
ใฏ
an
=
n-
(3
ใงใใใ
ใใใจ
1
1
1
(n=1,2,3, ...)
anan+1
ใช
an
an+1
3
1. (+1) (24+1)
ใๆใ็ซใคใใ
n(n+1)(24+1)
1
n
(n=1,2,3, ...)
ใซ
n+
ใญ
6
4
(2n+3n+1)
in ใงใใใ
n
(and high)
k=1akak+1
(ๆฐๅญฆII, ๆฐๅญฆB, ๆฐๅญฆC ็ฌฌ4ๅใฏๆฌกใใผใธใซ็ถใใ)