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

Terms

a(0) =1a(1) =0a(2) =0a(3) =0a(4) =6a(5) =36a(6) =0a(7) =324a(8) =0a(9) =324a(10) =0a(11) =36a(12) =12096a(13) =46656a(14) =81648a(15) =93960a(16) =69984a(17) =40824a(18) =11664a(19) =5832a(20) =0a(21) =216a(22) =17927568a(23) =64105344a(24) =109524960a(25) =117863424a(26) =89474544a(27) =49828608a(28) =21352896a(29) =6718464