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 | 1 |
| 2 | 5 |
| 3 | 30 |
| 4 | 195 |
| 5 | 1380 |
| 6 | 10555 |
| 7 | 86815 |
| 8 | 764350 |
| 9 | 7174420 |
| 10 | 71532369 |
| 11 | 755136887 |
| 12 | 8415519048 |
| 13 | 98744576456 |
| 14 | 1216948265335 |
| 15 | 15718032335081 |
| 16 | 212330461568282 |
| 17 | 2994374695258034 |
| 18 | 44008250794756373 |
| 19 | 672986694107199687 |
| 20 | 10692604102273015636 |
| 21 | 176266660430175342285 |