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 | 5 |
| 3 | 31 |
| 4 | 247 |
| 5 | 2927 |
| 6 | 40361 |
| 7 | 716167 |
| 8 | 14117683 |
| 9 | 334406399 |
| 10 | 9920878441 |
| 11 | 314016924901 |
| 12 | 11819186711467 |
| 13 | 492007393304957 |
| 14 | 21460568175640361 |
| 15 | 1021729465586766997 |
| 16 | 54766551458687142251 |
| 17 | 3263815694539731437539 |
| 18 | 201015517717077830328949 |
| 19 | 13585328068403621603022853 |