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 | 14 |
| 5 | 42 |
| 6 | 132 |
| 7 | 429 |
| 8 | 1430 |
| 9 | 4861 |
| 10 | 16784 |
| 11 | 58695 |
| 12 | 207452 |
| 13 | 739840 |
| 14 | 2658936 |
| 15 | 9620232 |
| 16 | 35011566 |
| 17 | 128082523 |
| 18 | 470731970 |
| 19 | 1737220254 |
| 20 | 6435115168 |
| 21 | 23918062480 |
| 22 | 89172805980 |
| 23 | 333396591075 |
| 24 | 1249717509612 |
| 25 | 4695654554206 |
| 26 | 17682176062376 |
| 27 | 66720743308877 |