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 | 1 |
| 4 | 6 |
| 5 | 28 |
| 6 | 114 |
| 7 | 432 |
| 8 | 1566 |
| 9 | 5517 |
| 10 | 19068 |
| 11 | 65044 |
| 12 | 219852 |
| 13 | 738316 |
| 14 | 2468028 |
| 15 | 8222805 |
| 16 | 27330858 |
| 17 | 90685224 |
| 18 | 300521622 |
| 19 | 994991716 |
| 20 | 3292117698 |
| 21 | 10887332473 |
| 22 | 35992718136 |
| 23 | 118958691528 |
| 24 | 393093822744 |
| 25 | 1298783453112 |
| 26 | 4290755845176 |
| 27 | 14174217683209 |
| 28 | 46821054068430 |
| 29 | 154655837126740 |