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 | 0 |
| 2 | 9 |
| 3 | 54 |
| 4 | 315 |
| 5 | 1836 |
| 6 | 10701 |
| 7 | 62370 |
| 8 | 363519 |
| 9 | 2118744 |
| 10 | 12348945 |
| 11 | 71974926 |
| 12 | 419500611 |
| 13 | 2445028740 |
| 14 | 14250671829 |
| 15 | 83059002234 |
| 16 | 484103341575 |
| 17 | 2821561047216 |
| 18 | 16445262941721 |
| 19 | 95850016603110 |
| 20 | 558654836676939 |
| 21 | 3256079003458524 |
| 22 | 18977819184074205 |
| 23 | 110610836100986706 |