Number of 2n-length words, either empty or beginning with the first character of an n-ary alphabet, that can be built by repeatedly inserting doublets into the initially empty word.

A248828

Number of 2n-length words, either empty or beginning with the first character of an n-ary alphabet, that can be built by repeatedly inserting doublets into the initially empty word.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =29a(4) =523a(5) =14289a(6) =530526a(7) =25066621a(8) =1443039123a(9) =98156060225

External references