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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 3 |
| 6 | 15 |
| 7 | 16 |
| 8 | 75 |
| 9 | 89 |
| 10 | 428 |
| 11 | 571 |
| 12 | 2781 |
| 13 | 4060 |
| 14 | 20093 |
| 15 | 31697 |
| 16 | 159340 |
| 17 | 268791 |
| 18 | 1372163 |
| 19 | 2455804 |
| 20 | 12725447 |
| 21 | 24012697 |
| 22 | 126238060 |
| 23 | 249880687 |
| 24 | 1332071241 |
| 25 | 2754348360 |
| 26 | 14881206473 |
| 27 | 32029000641 |
| 28 | 175297058228 |
| 29 | 391548016475 |
| 30 | 2169832010759 |