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) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 130 |
| 3 | 2574 |
| 4 | 25904 |
| 5 | 183200 |
| 6 | 1040112 |
| 7 | 5076400 |
| 8 | 22171648 |
| 9 | 88915968 |
| 10 | 333209600 |
| 11 | 1181548544 |
| 12 | 4001402880 |
| 13 | 13033885696 |
| 14 | 41061830656 |
| 15 | 125666611200 |
| 16 | 374947708928 |
| 17 | 1093874155520 |
| 18 | 3128047828992 |
| 19 | 8785866391552 |
| 20 | 24280799641600 |
| 21 | 66124498599936 |
| 22 | 177683966197760 |