A055326 Column 1 of triangle A055325.
1, -1, 3, -23, 425, -18129, 1721419, -353654167, 153923102577, -139765654884545, 261831303051976691, -1003756293946036677111, 7827579773381983088436313, -123626888505819540001029957073
Offset: 1
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.