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 | 2 |
| 2 | 4 |
| 3 | 9 |
| 4 | 25 |
| 5 | 89 |
| 6 | 403 |
| 7 | 2246 |
| 8 | 14887 |
| 9 | 114239 |
| 10 | 994909 |
| 11 | 9687123 |
| 12 | 104223700 |
| 13 | 1227484193 |
| 14 | 15703071262 |
| 15 | 216798771109 |
| 16 | 3212441188268 |
| 17 | 50845473960657 |
| 18 | 856063393693256 |
| 19 | 15276025334127835 |
| 20 | 287977916632275512 |