a1=m
a2=m+b...
a(2n+1)=m+2nb
S奇
=m(n+1)+n(2n+1)b
=75
S偶
=mn+2nnb
=60
a(n+1)=S奇-S偶=15
S=S奇+S偶=135
数列数(2n+1)=135/15=9
n=4
S偶
=4m+32b=60
a(n+1)=m+4b=15
b=0 m=15
数列9个15
a1=m
a2=m+b...
a(2n+1)=m+2nb
S奇
=m(n+1)+n(2n+1)b
=75
S偶
=mn+2nnb
=60
a(n+1)=S奇-S偶=15
S=S奇+S偶=135
数列数(2n+1)=135/15=9
n=4
S偶
=4m+32b=60
a(n+1)=m+4b=15
b=0 m=15
数列9个15