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 | 428 |
| 8 | 1428 |
| 9 | 4843 |
| 10 | 16704 |
| 11 | 58311 |
| 12 | 205731 |
| 13 | 732201 |
| 14 | 2625406 |
| 15 | 9473836 |
| 16 | 34375133 |
| 17 | 125325836 |
| 18 | 458831723 |
| 19 | 1686029403 |
| 20 | 6215738207 |
| 21 | 22981481106 |
| 22 | 85189188184 |
| 23 | 316514511424 |
| 24 | 1178424867416 |
| 25 | 4395603256233 |
| 26 | 16423417124023 |
| 27 | 61456310687426 |