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 | 3 |
| 4 | 16 |
| 5 | 122 |
| 6 | 1203 |
| 7 | 14518 |
| 8 | 207061 |
| 9 | 3406083 |
| 10 | 63465271 |
| 11 | 1320938774 |
| 12 | 30371545338 |
| 13 | 764447981599 |
| 14 | 20904838435264 |
| 15 | 617151430504113 |
| 16 | 19561785238965715 |
| 17 | 662583041367287249 |
| 18 | 23882958184429006800 |
| 19 | 912777131398463190802 |
| 20 | 36868849734952579404745 |