What is the thousandth term of S, a certain sequence of numbers?

[BTGModeratorVI]

What is the thousandth term of S, a certain sequence of numbers?

(1) For every n, the nth term of S is n^2.
(2) The first five terms of S are 1^2, 2^2, 3^2, 4^2, and 5^2.

Answer: A
Source: GMAT prep

[deloitte247]

$$T_{1000}=?$$
$$Statement\ 1=>For\ every\ m,\ the\ nth\ term\ of\ S\ is\ n^2$$
$$i.e\ T_n\ =\ n^2$$
$$\ T_1\ =\ 1^2$$
$$\ T_2\ =\ 2^2$$
$$\ T_{1000}=1000^2\ $$
$$=1000\cdot1000=1,000,000$$
Statement 1 is SUFFICIENT

$$Statement\ 2\ =>\ The\ first\ five\ term\ of\ \ S\ are\ 1^2,\ 2^2,3^2,4^2,\ and\ 5^2$$
Careful observation of the first 5 terms shows that they follow a general formula of Tn = n^2 but we are only limited to 5 terms and the statement does not tell us if this pattern remains true for the whole sequence of S. Hence T1000 is unknown and statement 2 is NOT SUFFICIENT

Since only statement 1 is SUFFICIENT
Answer = A

[Brent@GMATPrepNow]

What is the thousandth term of S, a certain sequence of numbers?

(1) For every n, the nth term of S is n^2.
(2) The first five terms of S are 1^2, 2^2, 3^2, 4^2, and 5^2.

Answer: A
Source: GMAT prep

Target question: What is the value of term_1000?

Statement 1: For every n, the nth term of S is n².
Perfect! Statement 1 provides a "recipe" for determining the value of ANY term in the sequence.
So, it must be the case that term_1000 = 1000² = 1,000,000
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: The first five terms of S are 1², 2², 3², 4², and 5².
Important: Even though it certainly LOOKS like there is a pattern here, we can't assume that it continues,
For example, the sequence COULD just be a list of someone's favorite numbers.
So, it COULD be the case that term_6 = 17², term_7 = 5.3, term_8 = -9.22, etc, in which case, term_1000 can have pretty much any value
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer: A

Cheers,
Brent