an=2an-1+n （n=2,3,.） （1）若｛an｝是等差数列,求｛an｝的通项公式

数列｛an},a1=1,an+1=2an-n^2+3n,求｛an｝. 在{an}中an>0 Sn=1/2（an+n/an）求an 已知数列｛an｝中a1=6,且an-an-1=(an-1/n)+n+1(n属于N*,n≥2）,求an 数列{an}中,a1=2,an+1=4an-3n+1,求证{an-n}是等比数列 4an中n为下标an+1中n+1为下标an-n中an的n为下标 设an=(1/n+1)+(1/n+2)+(1/n+3)+...+1/2n,则an+1-an等于? 已知数列{an},其中a1=1,a（n+1）=3^(2n-1)*an(n∈N),数列{bn}的前n项和Sn=log3(an/9^n)(n∈N)求an bn 若数列{an},a1=2/3,且a（n+1）=an+1/【（n+2）（n+1）】,（n∈N+）则通项an=? 已知A1=1,An=2An-1+n（n>1）,求An. 数列an满足a1=1/3,Sn=n(2n-1)an,求an 数列{an},a1=3,an*a(n+1)=(1/2)^n,求an 已知数列｛an｝中,a(n+1)=an+2^n,a1=3,求an 数列an中,若a（ n+1）=an+(2n-1)求an 裂项相消法求和（1）an=1/(2n+1)(2n+3)(2)an=5/n(n+2)(3)an=1/(n+1)(n+2)(4)an=2/n(n+1)四道题 裂项相消法求和（1）an=1/(2n+1)(2n+3)(2)an=5/n(n+2)(3)an=1/(n+1)(n+2)(4)an=2/n(n+1)四道题 an+1 ,n+1是下表 ,an+1=an^3 a1=2 ,求an 在数列an中,a1=2 an+1=an+3n则an= 数列｛an｝满足a1=1,且an=an-1+3n-2,求an 已知{an}满足a1=1.an=3*n+2An-1,求an 已知数列｛an｝满足a1=4/3,且an+1=〔4(n+1)an〕/(3an+n) (n∈N*)已知数列｛an｝满足a1=4/3,且an+1=〔4(n+1)an〕/(3an+n)(n∈N*).（1）求1/a1+2/a2+…+n/an的值；（2）求证：a1+a2/2+a3/3+…+an/n≤ n+ 7/12-(1/4)^n