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 | 1 |
| 2 | 4 |
| 3 | 28 |
| 4 | 250 |
| 5 | 2558 |
| 6 | 28594 |
| 7 | 340486 |
| 8 | 4255344 |
| 9 | 55300776 |
| 10 | 742732646 |
| 11 | 10267434138 |
| 12 | 145692400018 |
| 13 | 2118364506746 |
| 14 | 31529605958892 |
| 15 | 480186833802260 |
| 16 | 7483472464151002 |
| 17 | 119397596900634238 |
| 18 | 1951747376021480874 |
| 19 | 32721008993895160926 |
| 20 | 563260078608381337148 |
| 21 | 9967709437187109520736 |
| 22 | 181544883799333028286098 |
| 23 | 3406426523158387599683478 |
| 24 | 65894531117591548919270114 |