a(n) is the number of 3 X 3 matrices with elements 1..n where at least one row is strictly increasing.

A390904

a(n) is the number of 3 X 3 matrices with elements 1..n where at least one row is strictly increasing.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =2107a(4) =46144a(5) =432250a(6) =2548160a(7) =11135495a(8) =39398912a(9) =119084364a(10) =318528000a(11) =772705395a(12) =1730491840a(13) =3625678342a(14) =7179774784a(15) =13546271375a(16) =24507822080a(17) =42739759160a(18) =72155446272a(19) =118351228779a(20) =189171144000a(21) =295414111090a(22) =451709030080a(23) =677586082327

External references