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 | 0 |
| 2 | 1 |
| 3 | 4 |
| 4 | 23 |
| 5 | 162 |
| 6 | 1549 |
| 7 | 21090 |
| 8 | 446061 |
| 9 | 15673518 |
| 10 | 961338288 |
| 11 | 105752617892 |
| 12 | 21155707801451 |
| 13 | 7757777336382702 |
| 14 | 5245054939576054088 |
| 15 | 6571185585793205495484 |
| 16 | 15325133281701584879975433 |
| 17 | 66813349775478836190531605234 |
| 18 | 546646811841381587823502759339055 |