a(n) is the number of coverings of 1..n by cyclic words of length 3, such that each value from 1 to n appears precisely 3 times. That is, the union of all the letters in all of the words of a given covering is the multiset {1,1,1,2,2,2,...,n,n,n}. Repeats of words are allowed in a given covering.
A108242
a(n) is the number of coverings of 1..n by cyclic words of length 3, such that each value from 1 to n appears precisely 3 times. That is, the union of all the letters in all of the words of a given covering is the multiset {1,1,1,2,2,2,...,n,n,n}. Repeats of words are allowed in a given covering.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =16a(4) =256a(5) =7184a(6) =311944a(7) =19191448a(8) =1584972224a(9) =169021538944
External references
- oeis: A108242