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 | 6 |
| 3 | 16 |
| 4 | 60 |
| 5 | 305 |
| 6 | 1988 |
| 7 | 15951 |
| 8 | 153171 |
| 9 | 1722693 |
| 10 | 22296396 |
| 11 | 327270440 |
| 12 | 5381716953 |
| 13 | 98134088419 |
| 14 | 1967105567802 |
| 15 | 43024511648982 |
| 16 | 1020235144731236 |
| 17 | 26083065249549660 |
| 18 | 715430961891290714 |
| 19 | 20962974995245684878 |
| 20 | 653654392800091507791 |
| 21 | 21615444263990028093227 |