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 | 4 |
| 3 | 25 |
| 4 | 204 |
| 5 | 2065 |
| 6 | 24984 |
| 7 | 351841 |
| 8 | 5654440 |
| 9 | 102131761 |
| 10 | 2048289660 |
| 11 | 45164504281 |
| 12 | 1085996392404 |
| 13 | 28281070706785 |
| 14 | 792955976182384 |
| 15 | 23816960356178305 |
| 16 | 762935687373888144 |
| 17 | 25963630331068375201 |
| 18 | 935453627605835395380 |
| 19 | 35573201479352813399641 |
| 20 | 1423863512801718371381020 |