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) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 61 |
| 5 | 377 |
| 6 | 2734 |
| 7 | 22671 |
| 8 | 211035 |
| 9 | 2175754 |
| 10 | 24592551 |
| 11 | 302295925 |
| 12 | 4014475756 |
| 13 | 57277225309 |
| 14 | 873819665135 |
| 15 | 14195291340656 |
| 16 | 244657733062761 |
| 17 | 4459137940238245 |
| 18 | 85694418205589534 |
| 19 | 1731893273528613811 |
| 20 | 36721566227335477047 |
| 21 | 815098440677104096866 |