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 | 6 |
| 2 | 33 |
| 3 | 171 |
| 4 | 849 |
| 5 | 4083 |
| 6 | 19161 |
| 7 | 88203 |
| 8 | 399777 |
| 9 | 1789155 |
| 10 | 7923369 |
| 11 | 34780155 |
| 12 | 151526385 |
| 13 | 655905747 |
| 14 | 2823355257 |
| 15 | 12093944427 |
| 16 | 51582654273 |
| 17 | 219172472259 |
| 18 | 928100356425 |
| 19 | 3918172435419 |
| 20 | 16496161201041 |
| 21 | 69279692903091 |