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 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 118 |
| 6 | 675 |
| 7 | 4333 |
| 8 | 30464 |
| 9 | 230615 |
| 10 | 1856336 |
| 11 | 15738672 |
| 12 | 139509303 |
| 13 | 1285276242 |
| 14 | 12248071935 |
| 15 | 120255584181 |
| 16 | 1212503440774 |
| 17 | 12519867688928 |
| 18 | 132079067871313 |
| 19 | 1420723274988736 |
| 20 | 15554956521285848 |