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) |
|---|---|
| 4 | 1 |
| 5 | 3 |
| 6 | 19 |
| 7 | 143 |
| 8 | 1089 |
| 9 | 8564 |
| 10 | 69075 |
| 11 | 569469 |
| 12 | 4783377 |
| 13 | 40829748 |
| 14 | 353395155 |
| 15 | 3096104105 |
| 16 | 27415923905 |
| 17 | 245069538465 |
| 18 | 2209155012387 |
| 19 | 20064713628389 |
| 20 | 183478258249569 |
| 21 | 1688112897834496 |
| 22 | 15618577076864579 |
| 23 | 145242456429736935 |