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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 12 |
| 5 | 30 |
| 6 | 639 |
| 7 | 1835 |
| 8 | 64601 |
| 9 | 369518 |
| 10 | 12351620 |
| 11 | 78569754 |
| 12 | 5477440592 |
| 13 | 35108337731 |
| 14 | 3031753084624 |
| 15 | 30230571143624 |
| 16 | 3308601182539217 |
| 17 | 33507627807222128 |
| 18 | 5183154493935250901 |