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 | 0 |
| 1 | 1 |
| 2 | 6 |
| 3 | 51 |
| 4 | 542 |
| 5 | 6273 |
| 6 | 77262 |
| 7 | 991264 |
| 8 | 13109394 |
| 9 | 177428496 |
| 10 | 2445799878 |
| 11 | 34218909015 |
| 12 | 484668543660 |
| 13 | 6935979521095 |
| 14 | 100136840127534 |
| 15 | 1456726481340477 |
| 16 | 21332234689262126 |
| 17 | 314211310198197978 |
| 18 | 4652073871301311128 |
| 19 | 69194159284034697860 |
| 20 | 1033441834436615884266 |