# recursion – Obtaining numerical value from Recurrence Table

I’m trying to analyze the following sequence of numbers:

$$a_1 = 2 quad text{ s.t } quad a_n = 4sum_{i=1}^{n}a_i$$
I wrote the following code for creating a
Recurrence Table for this sequence of numbers:

``````rt = RecurrenceTable({a(n + 1) == 4 Sum(a(n), {1, n}), a(1) == 2}, a, {n, 1, 10})
``````

But, I’m facing the following issue, when I try to evaluate the actual numerical value, I’m getting the following format as output:

$$rt((2)) = 4 times sum_{1}^{1}2$$

Even when I run

``````N(rt((2))
``````

The output is

``````4. NSum(2, {1, 1})
``````

The ouput for the FullForm is:

``````!(
TagBox(
StyleBox(
RowBox({"Times", "(",
RowBox({"4", ",",
RowBox({"Sum", "(",
RowBox({"2", ",",
RowBox({"List", "(",
RowBox({"1", ",", "1"}), ")"})}), ")"})}), ")"}),
ShowSpecialCharacters->False,
ShowStringCharacters->True,
NumberMarks->True),
FullForm))
``````

Any tips on how to get the numerical values? Is the error in the actual function for the definition of the Recurrence Table?