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 | 4 |
| 1 | 20 |
| 2 | 88 |
| 3 | 416 |
| 4 | 2464 |
| 5 | 12320 |
| 6 | 73344 |
| 7 | 373248 |
| 8 | 2286080 |
| 9 | 11768320 |
| 10 | 72968192 |
| 11 | 378533888 |
| 12 | 2368397312 |
| 13 | 12353986560 |
| 14 | 77788119040 |
| 15 | 407431675904 |
| 16 | 2577750163456 |
| 17 | 13544806547456 |
| 18 | 86015627231232 |
| 19 | 453128543010816 |
| 20 | 2886172831383552 |