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 | 2 |
| 3 | 5 |
| 4 | 15 |
| 5 | 52 |
| 6 | 201 |
| 7 | 845 |
| 8 | 3801 |
| 9 | 18089 |
| 10 | 90316 |
| 11 | 470010 |
| 12 | 2536077 |
| 13 | 14127741 |
| 14 | 80966690 |
| 15 | 475979359 |
| 16 | 2863157581 |
| 17 | 17585971037 |
| 18 | 110095460224 |
| 19 | 701418693025 |
| 20 | 4541497543092 |
| 21 | 29847982448766 |
| 22 | 198913925919741 |
| 23 | 1342890255133042 |
| 24 | 9176456969273844 |
| 25 | 63422002415068463 |