已知数列{an}满足[a(n+1)+an-1]/[a(n+1)-an+1]=n,且a2=6
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[a+an-1]/[a-an+1]=n,

∴a+an-1=n(a-an+1),

(n-1)a=(n+1)an-n-1,

n=1时a1=1,

n>=2时a/[(n+1)n]=an/[n(n-1)]-1/[n(n-1),

即b=bn-1/(n-1)+1/n,b2=3,

b3=b2-1+1/2,

b4=b3-1/2+1/3,

……

bn=b-1/(n-2)+1/(n-1),

累加得bn=2+1/(n-1)=(2n-1)/(n-1).

综上,bn={3,n=1;

{(2n-1)/(n-1),n>=2.

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