If :

$\displaystyle \begin{cases} a(4)=2 \\ a(8)=50 \\ a(12)=102 \\a(20)=1104 \end{cases}$

what is $\displaystyle a(n)$ ?

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- Apr 12th 2012, 01:02 AMprincepsClosed form of a sequence
If :

$\displaystyle \begin{cases} a(4)=2 \\ a(8)=50 \\ a(12)=102 \\a(20)=1104 \end{cases}$

what is $\displaystyle a(n)$ ? - Apr 12th 2012, 01:42 AMa tutorRe: Closed form of a sequence
You haven't defined a sequence. You've only given a few terms.

You could use Lagrange interpolation to get a polynomial:

$\displaystyle a_n=2\frac{(n-8)(n-12)(n-20)}{(4-8)(4-12)(4-20)}+....$