Given the first n terms of sequence {an} and Sn = n ^ 2 + N + 1, is an arithmetic sequence?

Given the first n terms of sequence {an} and Sn = n ^ 2 + N + 1, is an arithmetic sequence?

a1=S1=3
a2=S2-S1=7-3=4
a3=S3-S2=13-7=6
an=Sn-S=[n^2+n+1]-[(n-1)^2+(n-1)+1]
=2n
The general formula of {an} is: A1 = 3, an = 2n (n = 2,3,...) )
The sequence {an} is not an arithmetic sequence,
But after the first term is removed, the sequence of other terms in order is the arithmetic sequence

Elden Ring Premiere

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