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 | 6 |
| 2 | 60 |
| 3 | 684 |
| 4 | 8270 |
| 5 | 103356 |
| 6 | 1319318 |
| 7 | 17089176 |
| 8 | 223742646 |
| 9 | 2953453860 |
| 10 | 39238422432 |
| 11 | 524028551976 |
| 12 | 7028512984012 |
| 13 | 94609733971200 |
| 14 | 1277433085844250 |
| 15 | 17293594106959920 |
| 16 | 234654019904185254 |
| 17 | 3190395630994096932 |
| 18 | 43454433346369902968 |
| 19 | 592805610973385781960 |