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 | 3 |
| 2 | 21 |
| 3 | 190 |
| 4 | 1950 |
| 5 | 21576 |
| 6 | 250971 |
| 7 | 3025308 |
| 8 | 37456650 |
| 9 | 473498025 |
| 10 | 6085977381 |
| 11 | 79296104784 |
| 12 | 1044955576496 |
| 13 | 13903071489300 |
| 14 | 186507160795350 |
| 15 | 2519857658331576 |
| 16 | 34258270557555282 |
| 17 | 468322722628414290 |
| 18 | 6433538749783033350 |
| 19 | 88767899653496377050 |
| 20 | 1229626632793564911906 |