The number of tight 5 X n pavings.

Terms

a(0) =0a(1) =1a(2) =57a(3) =1071a(4) =12279a(5) =106738a(6) =781458a(7) =5111986a(8) =30980370a(9) =178047831a(10) =985621119a(11) =5311715977a(12) =28075774881a(13) =146309927344a(14) =754544640000