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 | 5 |
| 3 | 31 |
| 4 | 270 |
| 5 | 3370 |
| 6 | 60146 |
| 7 | 1522031 |
| 8 | 54055976 |
| 9 | 2666453502 |
| 10 | 180847717069 |
| 11 | 16704822358932 |
| 12 | 2082808024263350 |
| 13 | 347639192485104658 |
| 14 | 77076883307827211845 |
| 15 | 22537752778732740525833 |
| 16 | 8633258320969387044105210 |
| 17 | 4305220991520242104331411368 |
| 18 | 2778601200692503839128415662124 |