OFFSET
1,1
COMMENTS
Two length-n sequences are considered to be the same in the cyclic sense if one is a cyclic shift of the other.
An abelian 4th power is a word of the form x x' x'' x''', where x', x'', x''' are all permutations of x.
EXAMPLE
a(7) = 10, and the cyclic words are {0001001, 0001011, 0001101, 0010011, 0010101, 0010111, 0011011, 0011101, 0101011, 0110111}.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jeffrey Shallit, Jun 05 2018
STATUS
approved