This is the same as the number of ways 8 nonnegative even integers sum to 12 (we subtract 1 from each integer in the above sum). All 11 possibilities are (leaving out 0s): 12, 10+2, 8+4, 8+2+2, 6+6, 6+4+2, 6+2+2+2+2, 4+4+4, 4+4+2+2, 4+2+2+2+2, 2+2+2+2+2+2.
Source: MathNet,
licensed CC-BY-4.0.
Statement reproduced verbatim; metadata (topic, difficulty, ordering) added by this project.