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 | 24 |
| 3 | 224 |
| 4 | 2464 |
| 5 | 29568 |
| 6 | 374528 |
| 7 | 4922368 |
| 8 | 66451968 |
| 9 | 915560448 |
| 10 | 12817846272 |
| 11 | 181780365312 |
| 12 | 2605518569472 |
| 13 | 37679807004672 |
| 14 | 549048616353792 |
| 15 | 8052713039855616 |
| 16 | 118777517337870336 |
| 17 | 1760702021714313216 |
| 18 | 26214896767746441216 |
| 19 | 391843720107367858176 |
| 20 | 5877655801610517872640 |