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 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 651 |
| 4 | 9765 |
| 5 | 109368 |
| 6 | 1057224 |
| 7 | 8649279 |
| 8 | 60544953 |
| 9 | 369776680 |
| 10 | 1996794072 |
| 11 | 9621890019 |
| 12 | 41694856749 |
| 13 | 163568562192 |
| 14 | 584173436400 |
| 15 | 1908310936455 |
| 16 | 5724932809365 |
| 17 | 15827726179440 |
| 18 | 40448633569680 |