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 | 44 |
| 3 | 486 |
| 4 | 3608 |
| 5 | 20330 |
| 6 | 93060 |
| 7 | 361550 |
| 8 | 1229360 |
| 9 | 3742290 |
| 10 | 10377180 |
| 11 | 26572086 |
| 12 | 63521352 |
| 13 | 143027898 |
| 14 | 305568564 |
| 15 | 623207070 |
| 16 | 1219605600 |
| 17 | 2300164770 |
| 18 | 4196289420 |
| 19 | 7428962950 |
| 20 | 12798246520 |
| 21 | 21507034122 |