OFFSET
0,3
EXAMPLE
a(0) = 1: the empty word.
a(1) = 1: aaaa.
a(2) = 19: aaaabbbb, aaababbb, aaabbabb, aaabbbab, aabaabbb, aabababb, aababbab, aabbaabb, aabbabab, abaaabbb, abaababb, abaabbab, ababaabb, abababab, baaaabbb, baaababb, baaabbab, baabaabb, baababab.
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Jun 23 2012
STATUS
approved