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 | 2 |
| 2 | 4 |
| 3 | 18 |
| 4 | 79 |
| 5 | 474 |
| 6 | 3166 |
| 7 | 24451 |
| 8 | 208702 |
| 9 | 1958407 |
| 10 | 19919811 |
| 11 | 217977667 |
| 12 | 2547895961 |
| 13 | 31638057367 |
| 14 | 415388265571 |
| 15 | 5743721766718 |
| 16 | 83356613617031 |
| 17 | 1265900592208029 |
| 18 | 20064711719120846 |
| 19 | 331153885800672577 |
| 20 | 5679210649417608867 |
| 21 | 101017359002718628295 |
| 22 | 1860460510677429522171 |