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 | 4 |
| 2 | 10 |
| 3 | 84 |
| 4 | 1140 |
| 5 | 7140 |
| 6 | 125580 |
| 7 | 2929290 |
| 8 | 161226780 |
| 9 | 2875585020 |
| 10 | 32451432090 |
| 11 | 9117204216120 |
| 12 | 173092525291140 |
| 13 | 12728365882372140 |
| 14 | 6235727798083743960 |
| 15 | 843456728066008506450 |
| 16 | 68313970807402942762140 |
| 17 | 7219596660397839675355860 |
| 18 | 211677272048242059920400540 |