a(n) = number of unicyclic connected simple graphs whose cycle has length 4.

A065889

a(n) = number of unicyclic connected simple graphs whose cycle has length 4.

Terms

    a(0) =3a(1) =60a(2) =1080a(3) =20580a(4) =430080a(5) =9920232a(6) =252000000a(7) =7015381560a(8) =212840939520

External references