Texas Instruments TI-84 - Manual (Page 161)

Chapter 6: Sequence Graphing 158
Recursive Sequences Recursive Sequences Recursive Sequences Recursive Sequences
In a recursive sequence, the n th term in the sequence is defined in relation to the
previous term or the term that precedes the previous term, represented by u(n
N
1) and
u(n N 2) . A recursive sequence may also be defined in relation to n , as in u(n)=u(n N 1)+n.
For example, in the sequence below you cannot calculate u(5) without first calculating
u(1) , u(2) , u(3) , and u(4) .
Using an initial value u(nMin) = 1 , the sequence above returns 1, 2, 4, 8, 16, ... .
Note: On the TI-84 Plus, you must type each character of the terms. For example, to
enter u(n
N
1) , press
y
[u]
£ „ ¹ À ¤.
Recursive sequences require an initial value or values, since they reference undefined
terms.
• If each term in the sequence is defined in relation to the previous term, as in u(n N 1) ,
you must specify an initial value for the first term.
• If each term in the sequence is defined in relation to the term that precedes the
previous term, as in
u(n
N
2) , you must specify initial values for the first two terms.