What comes next in the sequence?

Question

My roommate has insomnia so he was counting sheep to help him sleep.

He started with $2986$, then continued with $47786,\ 764586,$ and $12233386$.

What sequence is he following, and what was the next number?

Answer 1

The next number in the sequence is:

195 734 186

The sequence he is following is:

Hexadecimal numbers!

BAA = 2 986
BAAA = 47 786
BAAAA = 764 586
BAAAAA = 12 233 386
BAAAAAA = 195 734 186

Answer 2

I found it's

195734186

It's sequence where

k(n+1) = k(n) * 16 + 10

Answer 3

To add on to tansy's answer,

The sequence is: $$k(n+1) = 16 \cdot k(n) + 10$$ for the initial condition $k(1) = 2986$.

This recurrence equation can be solved as follows: $$k(n) = \frac{70 \cdot 2^{4 n + 3}}{3} - \frac{2}{3}$$ This formula can be used to calculate the $n^{th}$ value in this sequence for any value of $n$.

$$k(1) = 2986$$ $$k(2) = 47786$$ $$k(3) = 764586$$ $$k(4) = 12233386$$ $$k(5) = 195734186$$ $$\dots$$
The pattern of multiplying by 16 and adding 10 is the same as (in binary) performing a right-shift operation 4 times and then adding 1010. In hexadecimal, 4 bits is one digit and 1010 = A. In other words, $16\cdot k(n)+10\ $ takes the representation of $k(n)$ in hexadecimal and appends $\text{A}$.

$2986$ = $\text{BAA}$.
$47786 = \text{BAAA}$.
$764586 = \text{BAAAA}$.
$12233386 = \text{BAAAAA}$.
$195734186 = \text{BAAAAAA}$.

It makes sense that he would be using this sequence to count sheep since $\text{BAA}\dots$ is the sound the sheep make.