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 | 1 |
| 5 | 3 |
| 6 | 11 |
| 7 | 39 |
| 8 | 157 |
| 9 | 708 |
| 10 | 3543 |
| 11 | 19490 |
| 12 | 116943 |
| 13 | 760134 |
| 14 | 5320940 |
| 15 | 39907054 |
| 16 | 319256437 |
| 17 | 2713679718 |
| 18 | 24423117468 |
| 19 | 232019615953 |
| 20 | 2320196159531 |
| 21 | 24362059675078 |
| 22 | 267982656425859 |
| 23 | 3081800548897382 |
| 24 | 36981606586768593 |