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

Terms

a(0) =1a(1) =1a(2) =0a(3) =1a(4) =4a(5) =0a(6) =16a(7) =0a(8) =4a(9) =36a(10) =0a(11) =324a(12) =0a(13) =324a(14) =0a(15) =36a(16) =576a(17) =0a(18) =9216a(19) =0a(20) =20736a(21) =0a(22) =9216a(23) =0a(24) =576a(25) =14400a(26) =0a(27) =360000a(28) =0a(29) =1440000