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 | 2 |
| 2 | 6 |
| 3 | 24 |
| 4 | 136 |
| 5 | 1162 |
| 6 | 15702 |
| 7 | 346768 |
| 8 | 12836904 |
| 9 | 814033666 |
| 10 | 90074891654 |
| 11 | 17659668432744 |
| 12 | 6211830230882472 |
| 13 | 3960850942657072026 |
| 14 | 4617438765658479411542 |
| 15 | 9912250203901899238148640 |