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 | 1 |
| 2 | 7 |
| 3 | 50 |
| 4 | 399 |
| 5 | 3422 |
| 6 | 30798 |
| 7 | 286974 |
| 8 | 2744947 |
| 9 | 26798010 |
| 10 | 265945022 |
| 11 | 2674970684 |
| 12 | 27209385886 |
| 13 | 279412999031 |
| 14 | 2892787737002 |
| 15 | 30161921520976 |
| 16 | 316440334960563 |
| 17 | 3338105334701396 |
| 18 | 35385133077851602 |
| 19 | 376732207920371784 |
| 20 | 4026682585718602014 |