Number of rectangular arrangements of [1,3n] in 3 increasing sequences of size n and n monotonic sequences of size 3.

A185148

Number of rectangular arrangements of [1,3n] in 3 increasing sequences of size n and n monotonic sequences of size 3.

Terms

    a(0) =1a(1) =6a(2) =53a(3) =587a(4) =7572a(5) =109027a(6) =1705249a(7) =28440320a(8) =499208817a(9) =9134237407a(10) =172976239886

External references