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 | 28 |
| 4 | 239 |
| 5 | 3126 |
| 6 | 45990 |
| 7 | 823544 |
| 8 | 16711423 |
| 9 | 387440173 |
| 10 | 9990235398 |
| 11 | 285311670612 |
| 12 | 8913939907598 |
| 13 | 302875106592254 |
| 14 | 11111328602501550 |
| 15 | 437893920912786408 |
| 16 | 18446462594437808127 |
| 17 | 827240261886336764178 |
| 18 | 39346258082220810086373 |
| 19 | 1978419655660313589123980 |
| 20 | 104857499999905732078938574 |