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 | 24 |
| 3 | 207 |
| 4 | 1893 |
| 5 | 17952 |
| 6 | 174402 |
| 7 | 1723494 |
| 8 | 17250000 |
| 9 | 174354822 |
| 10 | 1776119970 |
| 11 | 18208500000 |
| 12 | 187659221409 |
| 13 | 1942674634371 |
| 14 | 20187543581880 |
| 15 | 210472842939975 |
| 16 | 2200677521078253 |
| 17 | 23068297001178240 |
| 18 | 242353695578011416 |
| 19 | 2551260130246575048 |
| 20 | 26905595698893121728 |