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 | 10 |
| 3 | 102 |
| 4 | 1342 |
| 5 | 19620 |
| 6 | 305004 |
| 7 | 4943352 |
| 8 | 82595376 |
| 9 | 1412486081 |
| 10 | 24602515801 |
| 11 | 434935956337 |
| 12 | 7783978950825 |
| 13 | 140752989839105 |
| 14 | 2567623696254905 |
| 15 | 47195200645619009 |
| 16 | 873239636055018809 |
| 17 | 16251426606785706209 |
| 18 | 304007720310330530081 |
| 19 | 5713101394865420846381 |