Number of 5-block bicoverings of an n-set.

Terms

a(0) =0a(1) =0a(2) =0a(3) =25a(4) =472a(5) =6185a(6) =70700a(7) =759045a(8) =7894992a(9) =80736625a(10) =817897300a(11) =8241325565a(12) =82783813112a(13) =830046591465