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) |
|---|---|
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 13 |
| 6 | 82 |
| 7 | 579 |
| 8 | 4752 |
| 9 | 43390 |
| 10 | 440192 |
| 11 | 4890741 |
| 12 | 59245120 |
| 13 | 775596313 |
| 14 | 10930514688 |
| 15 | 164806652728 |
| 16 | 2649865335040 |
| 17 | 45226435601207 |
| 18 | 817154768973824 |
| 19 | 15574618910994665 |
| 20 | 312426715251262464 |
| 21 | 6577619798222863696 |
| 22 | 145060238642780180480 |
| 23 | 3343382818203784146955 |