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 | 0 |
| 3 | 17 |
| 4 | 191 |
| 5 | 1816 |
| 6 | 16541 |
| 7 | 149320 |
| 8 | 1344880 |
| 9 | 12106148 |
| 10 | 108960347 |
| 11 | 980654368 |
| 12 | 8825914594 |
| 13 | 79433288194 |
| 14 | 714899721602 |
| 15 | 6434097782077 |
| 16 | 57906880685893 |
| 17 | 521161927629204 |
| 18 | 4690457351939133 |
| 19 | 42214116174823814 |
| 20 | 379927045590000351 |
| 21 | 3419343410347321718 |