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 | 18 |
| 3 | 76 |
| 4 | 312 |
| 5 | 1264 |
| 6 | 5088 |
| 7 | 20416 |
| 8 | 81792 |
| 9 | 327424 |
| 10 | 1310208 |
| 11 | 5241856 |
| 12 | 20969472 |
| 13 | 83881984 |
| 14 | 335536128 |
| 15 | 1342160896 |
| 16 | 5368676352 |
| 17 | 21474770944 |
| 18 | 85899214848 |
| 19 | 343597121536 |
| 20 | 1374389010432 |
| 21 | 5497557090304 |
| 22 | 21990230458368 |
| 23 | 87960926027776 |