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 | 0 |
| 2 | 2 |
| 3 | 30 |
| 4 | 302 |
| 5 | 2550 |
| 6 | 19502 |
| 7 | 140070 |
| 8 | 963902 |
| 9 | 6433590 |
| 10 | 41983502 |
| 11 | 269335110 |
| 12 | 1705278302 |
| 13 | 10686396630 |
| 14 | 66425568302 |
| 15 | 410223570150 |
| 16 | 2520229093502 |
| 17 | 15417960407670 |
| 18 | 93999281613902 |
| 19 | 571487645261190 |
| 20 | 3466523088409502 |
| 21 | 20987674370482710 |
| 22 | 126870924446280302 |