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 | 1 |
| 1 | 4 |
| 2 | 4 |
| 3 | 20 |
| 4 | 52 |
| 5 | 228 |
| 6 | 804 |
| 7 | 3444 |
| 8 | 13780 |
| 9 | 59588 |
| 10 | 253252 |
| 11 | 1113556 |
| 12 | 4892276 |
| 13 | 21860260 |
| 14 | 98055780 |
| 15 | 444148020 |
| 16 | 2021194260 |
| 17 | 9257373060 |
| 18 | 42583930500 |
| 19 | 196811777940 |
| 20 | 913015265460 |
| 21 | 4251135572580 |
| 22 | 19856669967780 |
| 23 | 93027410579700 |
| 24 | 436999575464532 |
| 25 | 2057978301836868 |
| 26 | 9713953354107844 |