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 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 25 |
| 4 | 121 |
| 5 | 583 |
| 6 | 2789 |
| 7 | 13287 |
| 8 | 63149 |
| 9 | 299697 |
| 10 | 1421107 |
| 11 | 6735253 |
| 12 | 31911985 |
| 13 | 151174893 |
| 14 | 716081551 |
| 15 | 3391722505 |
| 16 | 16064368343 |
| 17 | 76084921797 |
| 18 | 360353446761 |
| 19 | 1706695118265 |
| 20 | 8083167563465 |
| 21 | 38283027343193 |
| 22 | 181313615940197 |
| 23 | 858725280497117 |
| 24 | 4067034860337649 |