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 | 3 |
| 2 | 15 |
| 3 | 165 |
| 4 | 2145 |
| 5 | 36465 |
| 6 | 1057485 |
| 7 | 32782035 |
| 8 | 1344063435 |
| 9 | 57794727705 |
| 10 | 2716352202135 |
| 11 | 160264779925965 |
| 12 | 10737740255039655 |
| 13 | 783855038617894815 |
| 14 | 61924548050813690385 |
| 15 | 5139737488217536301955 |
| 16 | 519113486309971166497455 |
| 17 | 56583370007786857148222595 |
| 18 | 6393920810879914857749153235 |