Question

In: Statistics and Probability

Write the first four terms of the sequence defined by the recursive formula a1 = 2, an = an − 1 + n.

Write the first four terms of the sequence defined by the recursive formula a1 = 2, an = an − 1 + n.

Solutions

Expert Solution

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}.

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