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 | 0 |
| 2 | 0 |
| 3 | 2 |
| 4 | 14 |
| 5 | 117 |
| 6 | 1244 |
| 7 | 16340 |
| 8 | 256794 |
| 9 | 4708235 |
| 10 | 98765432 |
| 11 | 2334368214 |
| 12 | 61405650470 |
| 13 | 1779714835745 |
| 14 | 56358445438164 |
| 15 | 1936265501684072 |
| 16 | 71737338064426034 |
| 17 | 2851241711464855575 |
| 18 | 121019325106640638448 |
| 19 | 5463472083532379956970 |
| 20 | 261417839335180055401662 |
| 21 | 13215375398730198560266829 |