Card-matching numbers (Dinner-Diner matching numbers).

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =0a(5) =24a(6) =576a(7) =0a(8) =9216a(9) =0a(10) =20736a(11) =0a(12) =9216a(13) =0a(14) =576a(15) =4783104a(16) =25214976a(17) =62705664a(18) =98648064a(19) =109859328a(20) =87588864a(21) =54411264a(22) =23887872a(23) =9455616a(24) =1769472a(25) =663552a(26) =0a(27) =13824a(28) =248341303296