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) |
|---|---|
| 2 | 1 |
| 3 | 3 |
| 4 | 18 |
| 5 | 130 |
| 6 | 1125 |
| 7 | 11361 |
| 8 | 131124 |
| 9 | 1702548 |
| 10 | 24562575 |
| 11 | 389799355 |
| 12 | 6748339158 |
| 13 | 126565340694 |
| 14 | 2556332651145 |
| 15 | 55320126580005 |
| 16 | 1276961156453160 |
| 17 | 31318513972988008 |
| 18 | 813295166343147315 |
| 19 | 22293401161982239071 |
| 20 | 643251586018800611370 |
| 21 | 19488333337058966337930 |