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 | 19 |
| 2 | 399 |
| 3 | 7980 |
| 4 | 159980 |
| 5 | 3199581 |
| 6 | 63999600 |
| 7 | 1279991601 |
| 8 | 25599991620 |
| 9 | 511999832020 |
| 10 | 10239999832020 |
| 11 | 204799996632420 |
| 12 | 4095999996640419 |
| 13 | 81919999932640800 |
| 14 | 1638399999932648400 |
| 15 | 32767999998652808799 |
| 16 | 655359999998652816380 |
| 17 | 13107199999973052976380 |