This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | 2 |
| 6 | 40 |
| 7 | 0 |
| 8 | 703760 |
| 9 | 131328 |
| 10 | 300241541128192 |
| 11 | 0 |
| 12 | 28170013344558609991874248704 |
| 13 | 24595658799308603392 |
| 14 | 9502080486519653717758562294813775233459455787008 |
| 15 | 0 |