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 | 3 |
| 3 | 16 |
| 4 | 95 |
| 5 | 606 |
| 6 | 4032 |
| 7 | 27616 |
| 8 | 193167 |
| 9 | 1372930 |
| 10 | 9881498 |
| 11 | 71846160 |
| 12 | 526764680 |
| 13 | 3889340560 |
| 14 | 28888634400 |
| 15 | 215680108416 |
| 16 | 1617467908751 |
| 17 | 12177754012458 |
| 18 | 92004463332486 |
| 19 | 697263463622080 |
| 20 | 5298985086555090 |
| 21 | 40371796982444356 |