Number of 2-factors in C_4 X P_n.

Terms

a(0) =1a(1) =9a(2) =53a(3) =341a(4) =2169a(5) =13825a(6) =88093a(7) =561357a(8) =3577121a(9) =22794425a(10) =145252485a(11) =925589701a(12) =5898117961a(13) =37584466929a(14) =239498796653