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 | 30 |
| 2 | 495 |
| 3 | 5890 |
| 4 | 56265 |
| 5 | 456786 |
| 6 | 3263990 |
| 7 | 21017040 |
| 8 | 124018290 |
| 9 | 679118550 |
| 10 | 3484681077 |
| 11 | 16884109080 |
| 12 | 77731521980 |
| 13 | 341784289770 |
| 14 | 1441489548195 |
| 15 | 5852747363518 |
| 16 | 22948550618400 |
| 17 | 87131200662540 |
| 18 | 321100847115950 |
| 19 | 1150962640399770 |
| 20 | 4020058004480100 |
| 21 | 13704611801774340 |