Does there exists any simple connected graph G of order n, such that whenever λk is an eigenvalue of the adjacency matrix of G
Does there exists any simple connected graph G of order n, such that whenever λk is an eigenvalue of the adjacency matrix of G, kλ is also an eigenvalue of adjacency matrix of G. Here k is any positive natural number (k=1,2,3,4,5,…) and λ(≠0) is an eigenvalue of adjacency matrix of G.
Can any one help me with a SAGE code. (Also ( kλ, λk)) should have same multiplicity
For K=1, it is easy. But for k=2,3,4,…, how to write a SAGE code. Please help.
See code for a similar problem at https://ask.sagemath.org/question/59220/
I tried but could not ..Can you please help me out. Where to inset that k?