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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 33 |
| 6 | 192 |
| 7 | 1272 |
| 8 | 10182 |
| 9 | 90822 |
| 10 | 908160 |
| 11 | 9980160 |
| 12 | 119761980 |
| 13 | 1556766780 |
| 14 | 21794734080 |
| 15 | 326918753280 |
| 16 | 5230700053320 |
| 17 | 88921859605320 |
| 18 | 1600593472880640 |
| 19 | 30411275148656640 |
| 20 | 608225502973147920 |
| 21 | 12772735543856347920 |
| 22 | 281000181964839321600 |
| 23 | 6463004184741681561600 |