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 | 56 |
| 3 | 490 |
| 4 | 4508 |
| 5 | 42532 |
| 6 | 406112 |
| 7 | 3899224 |
| 8 | 37532432 |
| 9 | 361686640 |
| 10 | 3487250816 |
| 11 | 33630672544 |
| 12 | 324364881344 |
| 13 | 3128620091968 |
| 14 | 30177356271104 |
| 15 | 291080943932800 |
| 16 | 2807684251672832 |
| 17 | 27082179878242048 |
| 18 | 261227779725129728 |