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 | 28 |
| 4 | 191 |
| 5 | 1758 |
| 6 | 20552 |
| 7 | 292336 |
| 8 | 4902711 |
| 9 | 94682414 |
| 10 | 2068050286 |
| 11 | 50376290220 |
| 12 | 1353408261849 |
| 13 | 39741665020434 |
| 14 | 1266001712189172 |
| 15 | 43477659901096872 |
| 16 | 1601086339395521724 |
| 17 | 62931760277350226040 |
| 18 | 2629518833911705359016 |
| 19 | 116382349367962203872528 |
| 20 | 5439115134893599838307636 |