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 | 2 |
| 3 | 7 |
| 4 | 32 |
| 5 | 181 |
| 6 | 1232 |
| 7 | 9787 |
| 8 | 88832 |
| 9 | 907081 |
| 10 | 10291712 |
| 11 | 128445967 |
| 12 | 1748805632 |
| 13 | 25794366781 |
| 14 | 409725396992 |
| 15 | 6973071372547 |
| 16 | 126585529106432 |
| 17 | 2441591202059281 |
| 18 | 49863806091395072 |
| 19 | 1074927056650469527 |
| 20 | 24392086908129247232 |
| 21 | 581176736647853024581 |