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 | 3 |
| 2 | 12 |
| 3 | 90 |
| 4 | 702 |
| 5 | 5838 |
| 6 | 50895 |
| 7 | 458103 |
| 8 | 4225683 |
| 9 | 39745665 |
| 10 | 379730658 |
| 11 | 3674980518 |
| 12 | 35951809104 |
| 13 | 354950991006 |
| 14 | 3532167377340 |
| 15 | 35390917028619 |
| 16 | 356742401734236 |
| 17 | 3615164398809324 |
| 18 | 36809446799831823 |
| 19 | 376387507560832992 |
| 20 | 3863438843523528636 |
| 21 | 39794189982905311407 |