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 | 5 |
| 3 | 30 |
| 4 | 264 |
| 5 | 3135 |
| 6 | 46709 |
| 7 | 823564 |
| 8 | 16777528 |
| 9 | 387420759 |
| 10 | 10000003265 |
| 11 | 285311670666 |
| 12 | 8916100500148 |
| 13 | 302875106592331 |
| 14 | 11112006826381965 |
| 15 | 437893890380965260 |
| 16 | 18446744073726350224 |
| 17 | 827240261886336764313 |
| 18 | 39346408075296928032645 |