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 | 1 |
| 3 | 36 |
| 4 | 492 |
| 5 | 3608 |
| 6 | 18828 |
| 7 | 74760 |
| 8 | 250352 |
| 9 | 717984 |
| 10 | 1866558 |
| 11 | 4365580 |
| 12 | 9635472 |
| 13 | 19639032 |
| 14 | 38559416 |
| 15 | 71222616 |
| 16 | 128258496 |
| 17 | 219619968 |
| 18 | 370366101 |
| 19 | 597550068 |
| 20 | 955638824 |
| 21 | 1471571136 |
| 22 | 2253173892 |
| 23 | 3335433368 |
| 24 | 4932972864 |
| 25 | 7064391840 |
| 26 | 10133162774 |
| 27 | 14128072488 |
| 28 | 19743952032 |
| 29 | 26864847352 |