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 | 9 |
| 2 | 72 |
| 3 | 576 |
| 4 | 4572 |
| 5 | 36288 |
| 6 | 288036 |
| 7 | 2286144 |
| 8 | 18145260 |
| 9 | 144020016 |
| 10 | 1143094932 |
| 11 | 9072809424 |
| 12 | 72011403324 |
| 13 | 571558593312 |
| 14 | 4536492984324 |
| 15 | 36006402202848 |
| 16 | 285784857170316 |
| 17 | 2268290625889680 |
| 18 | 18003551393278836 |
| 19 | 142895208872692080 |