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 | 27 |
| 4 | 240 |
| 5 | 3094 |
| 6 | 45990 |
| 7 | 821484 |
| 8 | 16711680 |
| 9 | 387177517 |
| 10 | 9990293423 |
| 11 | 285263019633 |
| 12 | 8913939911695 |
| 13 | 302862111412779 |
| 14 | 11111328866154037 |
| 15 | 437889173336927557 |
| 16 | 18446462747068745474 |
| 17 | 827238010832411671962 |
| 18 | 39346258082152478030126 |