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 A334280 #19 Feb 16 2025 08:34:00
%S A334280 0,1,0,-1,1,0,-6,11,-6,1,0,-2790,7467,-7852,4300,-1346,244,-24,1,0,
%T A334280 -36586695600,132041735820,-208601259660,194243767689,-120509323400,
%U A334280 53195294240,-17371817260,4296667608,-815202340,119111090,-13339000,1127752,-69860,3000,-80,1
%N A334280 Irregular table read by rows: T(n, k) is the coefficient of x^k in the chromatic polynomial of the 1-skeleton of the n-dimensional demihypercube, 0 <= k <= 2^(n-1).
%H A334280 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/ChromaticPolynomial.html">Chromatic Polynomial</a>
%H A334280 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/HalvedCubeGraph.html">Halved Cube Graph</a>
%H A334280 Wikipedia, <a href="https://en.wikipedia.org/wiki/Demihypercube">Demihypercube</a>
%e A334280 n\k| 0 1 2 3 4 5 6 7 8
%e A334280 ---+----------------------------------------
%e A334280 1| 0 1
%e A334280 2| 0 -1 1
%e A334280 3| 0 -6 11 -6 1
%e A334280 4| 0 -2790 7467 -7852 4300 -1346 244 -24 1
%t A334280 T[n_, k_] := Coefficient[ChromaticPolynomial[GraphData[{"HalvedCube", n}], x], x, k]
%Y A334280 Cf. A048994 (simplex), A334278 (hypercube), A334279 (cross-polytope).
%K A334280 sign,tabf
%O A334280 1,7
%A A334280 _Peter Kagey_, Apr 22 2020