4704612119domain: NAppears in sequencesDuplicate of A003436.at n=10A000858Number of inequivalent labeled Hamiltonian circuits on n-octahedron. Interlacing chords joining 2n points on circle.at n=11A003436(2*n+1)*a(n+1) = (4*n^2+1)*a(n) + (2*n+1)*a(n-1) with n>1, a(0)=2, a(1)=-1.at n=11A231622