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 | 5 |
| 3 | 19 |
| 4 | 121 |
| 5 | 601 |
| 6 | 5641 |
| 7 | 35281 |
| 8 | 406561 |
| 9 | 3447361 |
| 10 | 45420481 |
| 11 | 439084801 |
| 12 | 7565564161 |
| 13 | 80951270401 |
| 14 | 1525654690561 |
| 15 | 20737536019201 |
| 16 | 421943967244801 |
| 17 | 6046686277632001 |
| 18 | 150482493928166401 |
| 19 | 2311256907767808001 |
| 20 | 61410502863943833601 |
| 21 | 1132546296081328128001 |