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 | 4 |
| 3 | 5 |
| 4 | 20 |
| 5 | 27 |
| 6 | 112 |
| 7 | 156 |
| 8 | 660 |
| 9 | 935 |
| 10 | 4004 |
| 11 | 5733 |
| 12 | 24752 |
| 13 | 35700 |
| 14 | 155040 |
| 15 | 224808 |
| 16 | 980628 |
| 17 | 1427679 |
| 18 | 6249100 |
| 19 | 9126975 |
| 20 | 40060020 |
| 21 | 58659315 |
| 22 | 258048960 |
| 23 | 378658800 |
| 24 | 1668903600 |
| 25 | 2453288292 |
| 26 | 10829900592 |
| 27 | 15944020316 |
| 28 | 70480305440 |
| 29 | 103897691640 |
| 30 | 459823234112 |