The sum of the first n terms of the sequence an is Sn = 4N (square) - N + 2. Find the general term formula of the sequence an

The sum of the first n terms of the sequence an is Sn = 4N (square) - N + 2. Find the general term formula of the sequence an

When a (n) = s (n) - S (n-1) = 8n-5 (n > = 2) n = 1, S1 = a (1) = 5

Given that the sequence {an} satisfies A1 = 1, (2n + 5) an + 1 - (2n + 7) an = 4n2 + 24N + 35 (n ∈ n *), then the general formula of the sequence {an} is___ ．

From the meaning of (2n + 5) an + 1 - (2n + 7) an = 4n2 + 24N + 35, we can get (2n + 5) an + 1 - (2n + 7) an = (2n + 5) (2n + 7), that is, an + 12 (n + 1) + 5-an2n + 5 = 1, so the sequence {an2n + 5} is an arithmetic sequence with A17 = 17 as the first term and 1 as the tolerance

If the general term formula of sequence an is an = 1 / N (n + 1), and the sum of the first n terms is Sn, then S100=

an=1/n-1/(n+1)
S100=a1+a2+.a100
=1-1/2+1/2-1/3+.1/99-1/100+1/100-1/101
=1-1/101
=(101-1)/101=100/101