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.
Row 5 of A355226 is 1, 16, 40. This means the 5-halved cube graph has independence polynomial 1 + 16*t + 40*t^2. Taking the alternating row sum of row 5, or evaluating the polynomial at -1, gives us 1 - 16 + 40 = 25 = a(5).
from sage.graphs.independent_sets import IndependentSets
def a(n):
if n == 1:
g = graphs.CompleteGraph(1)
else:
g = graphs.HalfCube(n)
icount=0
for Iset in IndependentSets(g):
if len(Iset) % 2 == 0:
icount += 1
else:
icount += -1
return icount
Comments