Chromatic invariant of the n-path complement graph.

Terms

a(0) =1a(1) =2a(2) =-1a(3) =0a(4) =1a(5) =5a(6) =28a(7) =182a(8) =1350a(9) =11274a(10) =104856a(11) =1076064a(12) =12086760a(13) =147561000a(14) =1946180160a(15) =27582811920a(16) =418131670320