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 | 2 |
| 3 | 6 |
| 4 | 24 |
| 5 | 119 |
| 6 | 705 |
| 7 | 4857 |
| 8 | 38142 |
| 9 | 336291 |
| 10 | 3289057 |
| 11 | 35337067 |
| 12 | 413698248 |
| 13 | 5241768017 |
| 14 | 71465060725 |
| 15 | 1043175024243 |
| 16 | 16231998346794 |
| 17 | 268207096127991 |
| 18 | 4690005160446721 |
| 19 | 86528908665043683 |
| 20 | 1679764981327051508 |
| 21 | 34226671269330933413 |
| 22 | 730361830628447403029 |