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 | 2 |
| 2 | 12 |
| 3 | 58 |
| 4 | 256 |
| 5 | 1072 |
| 6 | 4336 |
| 7 | 17112 |
| 8 | 66304 |
| 9 | 253280 |
| 10 | 956608 |
| 11 | 3579680 |
| 12 | 13292544 |
| 13 | 49039360 |
| 14 | 179912448 |
| 15 | 656874368 |
| 16 | 2388205568 |
| 17 | 8650598912 |
| 18 | 31231020032 |
| 19 | 112419973632 |
| 20 | 403596148736 |
| 21 | 1445463642112 |
| 22 | 5165581660160 |
| 23 | 18423238924288 |