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 | 1 |
| 3 | 4 |
| 4 | 11 |
| 5 | 66 |
| 6 | 302 |
| 7 | 2416 |
| 8 | 15619 |
| 9 | 156190 |
| 10 | 1310354 |
| 11 | 15724248 |
| 12 | 162512286 |
| 13 | 2275172004 |
| 14 | 27971176092 |
| 15 | 447538817472 |
| 16 | 6382798925475 |
| 17 | 114890380658550 |
| 18 | 1865385657780650 |
| 19 | 37307713155613000 |
| 20 | 679562217794156938 |
| 21 | 14950368791471452636 |