Number of words on {1,1,1,2,2,2,3,3,3,4,4,4,...,n,n,n} avoiding the pattern 1234.

A266737

Number of words on {1,1,1,2,2,2,3,3,3,4,4,4,...,n,n,n} avoiding the pattern 1234.

Terms

    a(0) =1a(1) =1a(2) =20a(3) =1680a(4) =173891a(5) =21347262a(6) =2977892253a(7) =455912368540

External references