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 | 18 |
| 2 | 180 |
| 3 | 900 |
| 4 | 3150 |
| 5 | 8820 |
| 6 | 21168 |
| 7 | 45360 |
| 8 | 89100 |
| 9 | 163350 |
| 10 | 283140 |
| 11 | 468468 |
| 12 | 745290 |
| 13 | 1146600 |
| 14 | 1713600 |
| 15 | 2496960 |
| 16 | 3558168 |
| 17 | 4970970 |
| 18 | 6822900 |
| 19 | 9216900 |
| 20 | 12273030 |
| 21 | 16130268 |
| 22 | 20948400 |
| 23 | 26910000 |
| 24 | 34222500 |
| 25 | 43120350 |
| 26 | 53867268 |
| 27 | 66758580 |
| 28 | 82123650 |
| 29 | 100328400 |
| 30 | 121777920 |