Texas Instruments TI-84 PLUS SILV Guidebook - Page 112

Nonrecursive Sequences In a nonrecursive sequence, the nth term is a function of the independent variable n. Each term is independent of all other terms. For example, in the nonrecursive sequence below, you can calculate u(5) directly, without first calculating u(1) or any previous term. The sequence equation above returns the sequence 2, 4, 6, 8, 10, ... for n = 1, 2, 3, 4, 5, ... . Note: You may leave blank the initial value u(nMin) when calculating nonrecursive sequences. Recursive Sequences In a recursive sequence, the nth term in the sequence is defined in relation to the previous term or the term that precedes the previous term, represented by u(nN1) and u(nN2). A recursive sequence may also be defined in relation to n, as in u(n)=u(nN1)+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(nN1), press y [u 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(nN1), you must specify an initial value for the first term. Chapter 6: Sequence Graphing 105