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 | 1 |
| 2 | 3 |
| 3 | 19 |
| 4 | 135 |
| 5 | 1291 |
| 6 | 14343 |
| 7 | 188539 |
| 8 | 2815095 |
| 9 | 47412811 |
| 10 | 886239783 |
| 11 | 18231365659 |
| 12 | 409053408855 |
| 13 | 9943622273131 |
| 14 | 260300948527623 |
| 15 | 7300927107288379 |
| 16 | 218426614502831415 |
| 17 | 6943261704033434251 |
| 18 | 233692323131307301863 |