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 | 1 |
| 3 | 3 |
| 4 | 6 |
| 5 | 10 |
| 6 | 30 |
| 7 | 105 |
| 8 | 280 |
| 9 | 756 |
| 10 | 2520 |
| 11 | 6930 |
| 12 | 18480 |
| 13 | 60060 |
| 14 | 180180 |
| 15 | 675675 |
| 16 | 2162160 |
| 17 | 6806800 |
| 18 | 24504480 |
| 19 | 77597520 |
| 20 | 232792560 |
| 21 | 888844320 |
| 22 | 3259095840 |
| 23 | 10708457760 |
| 24 | 37479602160 |
| 25 | 133855722000 |
| 26 | 435031096500 |
| 27 | 1445641797600 |
| 28 | 5059746291600 |
| 29 | 17468171721000 |
| 30 | 58227239070000 |