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 | 4 |
| 2 | 6 |
| 3 | 14 |
| 4 | 50 |
| 5 | 242 |
| 6 | 1682 |
| 7 | 13442 |
| 8 | 134402 |
| 9 | 1612802 |
| 10 | 22579202 |
| 11 | 361267202 |
| 12 | 6864076802 |
| 13 | 144145612802 |
| 14 | 3459494707202 |
| 15 | 93406357094402 |
| 16 | 2802190712832002 |
| 17 | 92472293523456002 |
| 18 | 3421474860367872002 |
| 19 | 136858994414714880002 |