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) |
|---|---|
| 1 | 1 |
| 2 | 9 |
| 3 | 50 |
| 4 | 318 |
| 5 | 1944 |
| 6 | 11963 |
| 7 | 73316 |
| 8 | 450096 |
| 9 | 2767118 |
| 10 | 17052653 |
| 11 | 105356398 |
| 12 | 652694106 |
| 13 | 4054512228 |
| 14 | 25254176312 |
| 15 | 157709971144 |
| 16 | 987358943331 |
| 17 | 6196330627807 |
| 18 | 38975339759358 |
| 19 | 245693231541360 |
| 20 | 1552021349807456 |
| 21 | 9823321416340666 |