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) |
|---|---|
| 4 | 1 |
| 5 | 1 |
| 6 | 3 |
| 7 | 11 |
| 8 | 37 |
| 9 | 125 |
| 10 | 421 |
| 11 | 1405 |
| 12 | 4637 |
| 13 | 15125 |
| 14 | 48777 |
| 15 | 155665 |
| 16 | 492157 |
| 17 | 1543269 |
| 18 | 4804663 |
| 19 | 14865495 |
| 20 | 45745953 |
| 21 | 140118817 |
| 22 | 427445507 |
| 23 | 1299383403 |
| 24 | 3937901525 |
| 25 | 11902380845 |
| 26 | 35891429675 |
| 27 | 108009437323 |
| 28 | 324455779889 |
| 29 | 973119941425 |