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 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 0 |
| 4 | 6 |
| 5 | 0 |
| 6 | 20 |
| 7 | 2 |
| 8 | 70 |
| 9 | 18 |
| 10 | 252 |
| 11 | 110 |
| 12 | 924 |
| 13 | 572 |
| 14 | 3434 |
| 15 | 2730 |
| 16 | 12902 |
| 17 | 12376 |
| 18 | 48926 |
| 19 | 54264 |
| 20 | 187036 |
| 21 | 232562 |
| 22 | 720062 |
| 23 | 980674 |
| 24 | 2789164 |
| 25 | 4086550 |
| 26 | 10861060 |
| 27 | 16878420 |
| 28 | 42484682 |
| 29 | 69242082 |
| 30 | 166823430 |
| 31 | 282580872 |
| 32 | 657178982 |
| 33 | 1148548016 |
| 34 | 2595874468 |