Number of 2-factors in P_6 X P_n.

Terms

a(0) =0a(1) =5a(2) =9a(3) =222a(4) =1140a(5) =13903a(6) =99051a(7) =972080a(8) =7826275a(9) =71053230a(10) =599141127a(11) =5285091303a(12) =45349095730a(13) =395755191515