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 | 1 |
| 2 | 2 |
| 3 | 15 |
| 4 | 60 |
| 5 | 319 |
| 6 | 1470 |
| 7 | 7267 |
| 8 | 34680 |
| 9 | 168435 |
| 10 | 810898 |
| 11 | 3921103 |
| 12 | 18918900 |
| 13 | 91381991 |
| 14 | 441150502 |
| 15 | 2130258075 |
| 16 | 10285325040 |
| 17 | 49663079099 |
| 18 | 239791814010 |
| 19 | 1157823924167 |
| 20 | 5590452446700 |
| 21 | 26993130847215 |
| 22 | 130334271942158 |