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 | 4 |
| 3 | 39 |
| 4 | 1080 |
| 5 | 88209 |
| 6 | 21493836 |
| 7 | 15683355351 |
| 8 | 34309958505840 |
| 9 | 225130514549271201 |
| 10 | 4431394012508602048404 |
| 11 | 261672339357326993189906439 |
| 12 | 46354644349343413982791427120040 |
| 13 | 24634789450813795903041020740742981169 |