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 | 7 |
| 2 | 52 |
| 3 | 406 |
| 4 | 3292 |
| 5 | 27412 |
| 6 | 232336 |
| 7 | 1991752 |
| 8 | 17197072 |
| 9 | 149138416 |
| 10 | 1296872512 |
| 11 | 11295848032 |
| 12 | 98485736896 |
| 13 | 859191307072 |
| 14 | 7498334401792 |
| 15 | 65453881499776 |
| 16 | 571430958514432 |
| 17 | 4989154870212352 |
| 18 | 43562344091309056 |
| 19 | 380371693248558592 |
| 20 | 3321335877279603712 |