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 | 1 |
| 2 | 5 |
| 3 | 29 |
| 4 | 192 |
| 5 | 1372 |
| 6 | 10314 |
| 7 | 80390 |
| 8 | 643774 |
| 9 | 5264984 |
| 10 | 43788393 |
| 11 | 369221844 |
| 12 | 3149085162 |
| 13 | 27119598885 |
| 14 | 235495141963 |
| 15 | 2059677411141 |
| 16 | 18127763268114 |
| 17 | 160433599528417 |
| 18 | 1426870597505859 |
| 19 | 12746368353418175 |
| 20 | 114316604199957112 |
| 21 | 1028937342955189009 |