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 | 3 |
| 3 | 7 |
| 4 | 20 |
| 5 | 52 |
| 6 | 152 |
| 7 | 432 |
| 8 | 1292 |
| 9 | 3876 |
| 10 | 11900 |
| 11 | 36856 |
| 12 | 115728 |
| 13 | 366348 |
| 14 | 1170280 |
| 15 | 3764080 |
| 16 | 12186584 |
| 17 | 39673332 |
| 18 | 129812956 |
| 19 | 426648632 |
| 20 | 1407939880 |
| 21 | 4663160064 |
| 22 | 15496048156 |
| 23 | 51650777864 |
| 24 | 172639344440 |
| 25 | 578511221636 |
| 26 | 1943155984792 |