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) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 45 |
| 4 | 365 |
| 5 | 2925 |
| 6 | 23405 |
| 7 | 187245 |
| 8 | 1497965 |
| 9 | 11983725 |
| 10 | 95869805 |
| 11 | 766958445 |
| 12 | 6135667565 |
| 13 | 49085340525 |
| 14 | 392682724205 |
| 15 | 3141461793645 |
| 16 | 25131694349165 |
| 17 | 201053554793325 |
| 18 | 1608428438346605 |
| 19 | 12867427506772845 |
| 20 | 102939420054182765 |