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 | 2 |
| 3 | 6 |
| 4 | 22 |
| 5 | 342 |
| 6 | 1444 |
| 7 | 33184 |
| 8 | 399235 |
| 9 | 12502550 |
| 10 | 117906198 |
| 11 | 7740054144 |
| 12 | 74673569118 |
| 13 | 4724493959332 |
| 14 | 121637216075836 |
| 15 | 4503600768557056 |
| 16 | 89450720590507768 |
| 17 | 10119960926575526448 |
| 18 | 152232968281237988010 |
| 19 | 16384000020089600480000 |
| 20 | 552020693349464673399080 |
| 21 | 35271474934322858202723576 |