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 | 0 |
| 2 | 1 |
| 3 | 25 |
| 4 | 267 |
| 5 | 2265 |
| 6 | 17471 |
| 7 | 128765 |
| 8 | 927067 |
| 9 | 6591505 |
| 10 | 46545591 |
| 11 | 327428805 |
| 12 | 2298406067 |
| 13 | 16114352345 |
| 14 | 112902172111 |
| 15 | 790721005645 |
| 16 | 5536667136267 |
| 17 | 38763140938785 |
| 18 | 271367842141031 |
| 19 | 1899678231827285 |
| 20 | 13298160713181667 |