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 | 2 |
| 3 | 15 |
| 4 | 76 |
| 5 | 325 |
| 6 | 1266 |
| 7 | 4655 |
| 8 | 16472 |
| 9 | 56745 |
| 10 | 191710 |
| 11 | 638275 |
| 12 | 2101188 |
| 13 | 6855485 |
| 14 | 22205834 |
| 15 | 71498775 |
| 16 | 229058224 |
| 17 | 730680145 |
| 18 | 2322163638 |
| 19 | 7356008555 |
| 20 | 23234743580 |
| 21 | 73200452325 |
| 22 | 230081633122 |
| 23 | 721667902015 |
| 24 | 2259234965256 |
| 25 | 7060318981625 |
| 26 | 22028631430286 |
| 27 | 68628565425555 |
| 28 | 213512971483252 |