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 | 2 |
| 1 | 3 |
| 2 | 7 |
| 3 | 22 |
| 4 | 89 |
| 5 | 446 |
| 6 | 2677 |
| 7 | 18740 |
| 8 | 149921 |
| 9 | 1349290 |
| 10 | 13492901 |
| 11 | 148421912 |
| 12 | 1781062945 |
| 13 | 23153818286 |
| 14 | 324153456005 |
| 15 | 4862301840076 |
| 16 | 77796829441217 |
| 17 | 1322546100500690 |
| 18 | 23805829809012421 |
| 19 | 452310766371236000 |
| 20 | 9046215327424720001 |
| 21 | 189970521875919120022 |