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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 9 |
| 7 | 76 |
| 8 | 542 |
| 9 | 3523 |
| 10 | 21392 |
| 11 | 123680 |
| 12 | 690541 |
| 13 | 3756151 |
| 14 | 20042513 |
| 15 | 105394295 |
| 16 | 548123440 |
| 17 | 2826435403 |
| 18 | 14479201301 |
| 19 | 73794961960 |
| 20 | 374603863517 |
| 21 | 1895632969275 |
| 22 | 9568915248589 |
| 23 | 48208452866816 |