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 | 4 |
| 2 | 28 |
| 3 | 220 |
| 4 | 1819 |
| 5 | 15484 |
| 6 | 134320 |
| 7 | 1180764 |
| 8 | 10482340 |
| 9 | 93766288 |
| 10 | 843822148 |
| 11 | 7631018564 |
| 12 | 69291185474 |
| 13 | 631334484200 |
| 14 | 5769124912320 |
| 15 | 52851389067420 |
| 16 | 485242722376524 |
| 17 | 4463782855666480 |
| 18 | 41133265444555120 |