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.
%I A306839 #13 May 27 2024 06:50:23
%S A306839 2,40,6960,10340736,129599358720,13527918439695360
%N A306839 Number of unimodular n X n matrices with elements {-1, 0, 1}.
%H A306839 S. E. Thornton, <a href="http://www.bohemianmatrices.com/cpdb/unstructured/unstructured_n1_0_1">Properties of the Bohemian family of n x n matrices with population {-1, 0, 1}</a>, Characteristic Polynomial Database.
%H A306839 Minfeng Wang, <a href="/A306839/a306839.cpp.txt">C++ program to calculate A306839</a>
%K A306839 nonn,more,hard
%O A306839 1,1
%A A306839 _Steven E. Thornton_, Mar 12 2019
%E A306839 a(1)-a(5) confirmed and a(6) added by _Minfeng Wang_, May 01 2024