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 | 5 |
| 2 | 45 |
| 3 | 162 |
| 4 | 689 |
| 5 | 4505 |
| 6 | 20842 |
| 7 | 104969 |
| 8 | 623549 |
| 9 | 3195095 |
| 10 | 16779202 |
| 11 | 94570299 |
| 12 | 502818683 |
| 13 | 2684335804 |
| 14 | 14798497776 |
| 15 | 79585694357 |
| 16 | 428251526577 |
| 17 | 2337808909399 |
| 18 | 12622803157240 |
| 19 | 68178468555088 |
| 20 | 370527376656027 |
| 21 | 2003864441765404 |