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 | 23 |
| 6 | 1104 |
| 7 | 16945 |
| 8 | 141696 |
| 9 | 810746 |
| 10 | 3568352 |
| 11 | 12948318 |
| 12 | 40514560 |
| 13 | 112720393 |
| 14 | 285073712 |
| 15 | 666143975 |
| 16 | 1456288512 |
| 17 | 3007576740 |
| 18 | 5913372864 |
| 19 | 11138305068 |
| 20 | 20202100224 |
| 21 | 35433809451 |
| 22 | 60316600080 |
| 23 | 99947225741 |
| 24 | 161638967424 |
| 25 | 255701773822 |
| 26 | 396439174560 |
| 27 | 603407582570 |