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 | 1 |
| 2 | 9 |
| 3 | 113 |
| 4 | 1649 |
| 5 | 26225 |
| 6 | 440985 |
| 7 | 7711009 |
| 8 | 138792929 |
| 9 | 2554489505 |
| 10 | 47854963881 |
| 11 | 909495557393 |
| 12 | 17492724268369 |
| 13 | 339846019830673 |
| 14 | 6659441891042105 |
| 15 | 131467175048437569 |
| 16 | 2612224160086781889 |
| 17 | 52201209713045788737 |
| 18 | 1048450942860766632777 |
| 19 | 21153308764742204273329 |
| 20 | 428520989167282737342513 |