General Term of Arithmetic Sequences

\(t_n = t_1 + (n - 1)d \)

\(t_1 \) is the first term of the sequence
\(n \) is the number of terms
\(d \) is the common difference \((d = t_n - t_{n - 1}) \)
\(t_n \) is the general term, or \(n^{th} \) term

For the alkanes, the general term for the number of hydrogen atoms is:

\(t_n = t_1 + (n - 1)d \)
\(t_n = 4 + (n - 1)2 \)
\(t_n = 4 + 2n - 2 \)
\(t_n = 2 + 2n \)

where \(n \) is the number of carbon atoms and \(t_n \) is the number of hydrogen atoms.