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 | 3 |
| 3 | 12 |
| 4 | 69 |
| 5 | 538 |
| 6 | 5404 |
| 7 | 67092 |
| 8 | 997581 |
| 9 | 17337444 |
| 10 | 345547750 |
| 11 | 7778860028 |
| 12 | 195365725310 |
| 13 | 5418540898800 |
| 14 | 164556820433116 |
| 15 | 5432639292242576 |
| 16 | 193765826638479112 |
| 17 | 7426524928340527902 |
| 18 | 304439910637309354106 |
| 19 | 13293321078232321952036 |
| 20 | 616016966059346344408690 |
| 21 | 30196821383142448481822800 |