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 | 1 |
| 2 | 3 |
| 3 | 15 |
| 4 | 97 |
| 5 | 738 |
| 6 | 6297 |
| 7 | 58630 |
| 8 | 585543 |
| 9 | 6200916 |
| 10 | 69071103 |
| 11 | 804470751 |
| 12 | 9753459717 |
| 13 | 122670681073 |
| 14 | 1596129692136 |
| 15 | 21437840848440 |
| 16 | 296680980737270 |
| 17 | 4224090724829151 |
| 18 | 61794432127467450 |
| 19 | 927795254532531834 |
| 20 | 14282871462981487854 |
| 21 | 225247807261125989496 |
| 22 | 3636185180695164503129 |