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 | 15 |
| 2 | 154 |
| 3 | 1350 |
| 4 | 10890 |
| 5 | 83650 |
| 6 | 623056 |
| 7 | 4547520 |
| 8 | 32735085 |
| 9 | 233369675 |
| 10 | 1652203542 |
| 11 | 11638252730 |
| 12 | 81674873553 |
| 13 | 571575363975 |
| 14 | 3991529920440 |
| 15 | 27829484027400 |
| 16 | 193791573179883 |
| 17 | 1348196149698885 |
| 18 | 9372495529924710 |
| 19 | 65120144658997050 |
| 20 | 452263192928596896 |