In: Statistics and Probability
Write the first four terms of the sequence defined by the recursive formula a1 = 2, an = an − 1 + n.
Consider a sequence defined by the recursive formula,
a1 = 2
an = an-1 + n
First term of the sequence is,
a1 = 2
Substitute n = 1 and a1 = 2 in formula an = an-1 + n and compute second term of the sequence,
a2 = a1 + 2
= 2 + 2
= 4
Substitute n = 3 and a2 = 4 in formula an = an-1 + n and compute third term of the sequence,
a3 = a2 + 3
= 4 + 3
= 7
Substitute n = 4 and a3 = 7 in formula an = an-1 + n and compute fourth term of the sequence,
a4 = a3 + 4
= 7 + 4
= 11
Therefore, first four terms of the given sequence are {2, 4, 7, 11}.
Therefore, first four terms of the given sequence are {2, 4, 7, 11}.