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) |
|---|---|
| 5 | 3 |
| 6 | 21 |
| 7 | 135 |
| 8 | 702 |
| 9 | 3402 |
| 10 | 15282 |
| 11 | 65610 |
| 12 | 270540 |
| 13 | 1082565 |
| 14 | 4221639 |
| 15 | 16120377 |
| 16 | 60450138 |
| 17 | 223205220 |
| 18 | 813100356 |
| 19 | 2927177028 |
| 20 | 10428053400 |
| 21 | 36804946455 |
| 22 | 128817263385 |
| 23 | 447470664795 |
| 24 | 1543773631158 |
| 25 | 5292938720718 |
| 26 | 18044108743734 |
| 27 | 61193066237550 |