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 | 18 |
| 2 | 198 |
| 3 | 1716 |
| 4 | 12870 |
| 5 | 87516 |
| 6 | 554268 |
| 7 | 3325608 |
| 8 | 19122246 |
| 9 | 106234700 |
| 10 | 573667380 |
| 11 | 3024791640 |
| 12 | 15628090140 |
| 13 | 79342611480 |
| 14 | 396713057400 |
| 15 | 1957117749840 |
| 16 | 9540949030470 |
| 17 | 46021048264620 |
| 18 | 219878341708740 |
| 19 | 1041528987041400 |
| 20 | 4895186239094580 |
| 21 | 22844202449108040 |