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 | 12 |
| 2 | 132 |
| 3 | 1452 |
| 4 | 15906 |
| 5 | 174240 |
| 6 | 1908720 |
| 7 | 20908800 |
| 8 | 229042770 |
| 9 | 2509019700 |
| 10 | 27484733100 |
| 11 | 301077971700 |
| 12 | 3298119892650 |
| 13 | 36128829891000 |
| 14 | 395768617233000 |
| 15 | 4335396381723000 |
| 16 | 47491541694374250 |
| 17 | 520239981289297500 |