Calculus 2 Sequences

Question

Write out the first 5 terms of the sequence given by an = n^2 + 2n − 3

Find a closed formula for the sequence (starting with a1 ) 4,10,18,28,...

Answer 1

n = 1, a₁ = 1; n = 2 a₂ = 5, n = 3; a₃ = 12; n = 4, a₄ = 21; n = 5, a₅ = 32.

a_n = n(n + 3), this is general term of sequence: 4, 10, 18, 28, ...