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 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 20 |
| 5 | 70 |
| 6 | 252 |
| 7 | 924 |
| 8 | 3432 |
| 9 | 12705 |
| 10 | 45430 |
| 11 | 152438 |
| 12 | 472836 |
| 13 | 1352078 |
| 14 | 3578680 |
| 15 | 8827080 |
| 16 | 20439984 |
| 17 | 44745513 |
| 18 | 93185994 |
| 19 | 185640070 |
| 20 | 355452020 |
| 21 | 656846190 |
| 22 | 1175604980 |
| 23 | 2044130980 |
| 24 | 3462303000 |
| 25 | 5725877625 |
| 26 | 9264588606 |
| 27 | 14692562262 |
| 28 | 22874204836 |
| 29 | 35009334470 |