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 | 13 |
| 3 | 72 |
| 4 | 429 |
| 5 | 2601 |
| 6 | 15534 |
| 7 | 93339 |
| 8 | 559845 |
| 9 | 3359232 |
| 10 | 20155473 |
| 11 | 120932109 |
| 12 | 725594598 |
| 13 | 4353563943 |
| 14 | 26121388761 |
| 15 | 156728328192 |
| 16 | 940369966965 |
| 17 | 5642219821473 |
| 18 | 33853318876350 |
| 19 | 203119913356515 |
| 20 | 1218719480001309 |