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 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 1 |
| 6 | 6 |
| 7 | 30 |
| 8 | 136 |
| 9 | 566 |
| 10 | 2176 |
| 11 | 7808 |
| 12 | 26440 |
| 13 | 85332 |
| 14 | 264632 |
| 15 | 793792 |
| 16 | 2315136 |
| 17 | 6592640 |
| 18 | 18390784 |
| 19 | 50392064 |
| 20 | 135921664 |
| 21 | 361536512 |
| 22 | 949708800 |
| 23 | 2466807808 |
| 24 | 6342115328 |
| 25 | 16153509888 |
| 26 | 40790523904 |
| 27 | 102186352640 |
| 28 | 254105092096 |
| 29 | 627533152256 |
| 30 | 1539764125696 |