What is the next number in the sequence: 12, 15, 20, 24?

Sequence: 12 15 20 24

The next number is: 36

Rule:

Each term is: The nth prime, written in base three,

if the result is even then 11 or if it is odd then 8, plus n squared

The first 50 terms (starting from n = 1) are:

12 15 20 24 36 44 60 72 92 111 129 152 180 204 236 267 300 332 369 411 449 492 540 587 633 687 737 795 849 911 969 1035 1100 1164 1236 1304 1377 1452 1532 1611 1692 1772 1860 1944 2036 2124 2217 2312 2412 2508

Example:

To get the value for n = 12:

Find the twelfth prime, giving 37.

Write the number in base three, giving 1101.

This is odd, giving 8.

Add the original number squared, giving 152.

So the result is 152.

12, 15, 20, 24, 30, 35, 42, 48, etc.