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 | 1 |
| 3 | 4 |
| 4 | 23 |
| 5 | 166 |
| 6 | 1380 |
| 7 | 12684 |
| 8 | 125857 |
| 9 | 1328084 |
| 10 | 14754242 |
| 11 | 171338020 |
| 12 | 2069009164 |
| 13 | 25877555908 |
| 14 | 334197713580 |
| 15 | 4445788022944 |
| 16 | 60800921601639 |
| 17 | 853479846713406 |
| 18 | 12280659254071964 |
| 19 | 180929894848439516 |
| 20 | 2726751302240331150 |
| 21 | 42001984460083899448 |
| 22 | 660800371941797598828 |