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 | 1 |
| 2 | 6 |
| 3 | 44 |
| 4 | 360 |
| 5 | 3152 |
| 6 | 28896 |
| 7 | 273856 |
| 8 | 2661504 |
| 9 | 26380544 |
| 10 | 265655808 |
| 11 | 2710244352 |
| 12 | 27952883712 |
| 13 | 290977271808 |
| 14 | 3053105307648 |
| 15 | 32256844087296 |
| 16 | 342870535471104 |
| 17 | 3664053076557824 |
| 18 | 39342496410894336 |
| 19 | 424243929700630528 |
| 20 | 4592400943255388160 |
| 21 | 49885822426526253056 |