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 | 3 |
| 4 | 16 |
| 5 | 108 |
| 6 | 836 |
| 7 | 7136 |
| 8 | 65708 |
| 9 | 643522 |
| 10 | 6638880 |
| 11 | 71649726 |
| 12 | 804833052 |
| 13 | 9373104396 |
| 14 | 112833093984 |
| 15 | 1400634016520 |
| 16 | 17894022203641 |
| 17 | 234907670711601 |
| 18 | 3164596264280695 |
| 19 | 43700481254733535 |
| 20 | 617995260359761384 |
| 21 | 8942391804824517624 |
| 22 | 132304132524112742604 |