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 | 6 |
| 2 | 15 |
| 3 | 50 |
| 4 | 210 |
| 5 | 456 |
| 6 | 4220 |
| 7 | 6960 |
| 8 | 57330 |
| 9 | 188810 |
| 10 | 1518558 |
| 11 | 3302916 |
| 12 | 45916780 |
| 13 | 83747280 |
| 14 | 933074430 |
| 15 | 3920355200 |
| 16 | 22075393725 |
| 17 | 62230996500 |
| 18 | 940379117630 |
| 19 | 1781757016320 |
| 20 | 22856963695482 |
| 21 | 87052415634120 |