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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 13 |
| 5 | 114 |
| 6 | 1509 |
| 7 | 25595 |
| 8 | 535753 |
| 9 | 13305590 |
| 10 | 382728552 |
| 11 | 12515198465 |
| 12 | 458621603279 |
| 13 | 18619063906689 |
| 14 | 829607273337513 |
| 15 | 40253392454978755 |
| 16 | 2112878091130119496 |
| 17 | 119296114546292088543 |
| 18 | 7209829960147215492897 |
| 19 | 464413707136960430809460 |
| 20 | 31762965767675300603026848 |