An=1∕1+2+3+...+(2n-1),（n属于N+）,则A3=

数列｛an},a1=1,an+1=2an-n^2+3n,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? 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 an+1 ,n+1是下表 ,an+1=an^3 a1=2 ,求an 数列｛an｝满足a1=1,且an=an-1+3n-2,求an 在数列an中,a1=2 an+1=an+3n则an= 已知{an}满足a1=1.an=3*n+2An-1,求an 数列{an}满足a1=1 an+1=2n+1an/an+2n 数列{an}中,a1=1,an+1/an=n/n+2,求an 数列an,an=(2n-1)+1/【3n(n+1)】,求Sn an=(3n-2)(1/2)^(n-1),求{an}前n项和 已知a1=2 a(n+1)=2an+2^n+3^n 求an 一道数学题、、数列{an}：a1=4,an=3an-1+2n-1,n≥2求an. 数列{an}满足a1=1,an=3n+2an-1(n≥2)求an 在数列{an}中,a1=1,a2=5,an+2=an+1-an (n∈N*), 则a100等于an+2=an+1-an,an+3=an+2-an+1, 两式相加可得an在数列{an}中,a1=1,a2=5,an+2=an+1-an (n∈N*), 则a100等于( )方法一: an+2=an+1-an,an+3=an+2-an+1, 两式相加