Number of ways four L-tiles can be placed on an n X n square.

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =1a(5) =176a(6) =3145a(7) =22969a(8) =106819a(9) =376796a(10) =1101151a(11) =2805825a(12) =6438909a(13) =13602304a(14) =26866541a(15) =50186401a(16) =89436655a(17) =153088924a(18) =253052339a(19) =405702361a(20) =633123801a(21) =964595760a(22) =1438347889a(23) =2103619049a(24) =3023051131a(25) =4275452476a(26) =5958967015a(27) =8194686929a(28) =11130748309