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 | 12 |
| 2 | 54 |
| 3 | 198 |
| 4 | 842 |
| 5 | 3622 |
| 6 | 15984 |
| 7 | 71468 |
| 8 | 323042 |
| 9 | 1472022 |
| 10 | 6751064 |
| 11 | 31123148 |
| 12 | 144092684 |
| 13 | 669468708 |
| 14 | 3119587196 |
| 15 | 14572658668 |
| 16 | 68216250402 |
| 17 | 319893194558 |
| 18 | 1502357897232 |
| 19 | 7064711394284 |
| 20 | 33257109397452 |
| 21 | 156701323391972 |