a(n) is the number of coverings of 1..n by cyclic words of length n, 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 not allowed in a given covering.
A110105
a(n) is the number of coverings of 1..n by cyclic words of length n, 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 not allowed in a given covering.
Terms
- a(0) =1a(1) =1a(2) =2a(3) =12a(4) =192a(5) =5744a(6) =260904a(7) =16542648a(8) =1395722688a(9) =151232990208
External references
- oeis: A110105