OFFSET
2,2
LINKS
T. W. Cusick, P. Stanica, Counting the n-chromos of I.J. Schoenberg, Journal of Combinatorial Theory, Ser. A, Vol. 79, No. 2, pp. 298-314.
P. Stanica, Chromos and covering residue classes, preprint, Dec., 1999.
EXAMPLE
a(2)=1 because 12 is the only chromo with two colors, a(3)=2 because 123 and 122133 are the only chromos with three colors.
CROSSREFS
KEYWORD
hard,more,nice,nonn
AUTHOR
Pantelimon Stanica (pstanica(AT)mail.aum.edu)
EXTENSIONS
Next term is >=27.
STATUS
approved