OFFSET
1,3
COMMENTS
Equivalence is up to permutation of the colors.
EXAMPLE
a(2) = 1: (12).
a(3) = 3: (112), (1(12)), (1(22)).
a(4) = 17: (1112), (1122), (11(12)), (11(22)), (12(11)), (12(12)), (1(112)), (1(122)), (1(222)), (1(1(12))), (1(1(22))), (1(2(11))), (1(2(12))), (1(2(22))), ((11)(12)), ((11)(22)), ((12)(12)).
PROG
(PARI) \\ See A339647 for cycleIndexSeries and InequivalentColoringsSeq.
{ my(S=cycleIndexSeries(20)); InequivalentColoringsSeq(S, 2) - InequivalentColoringsSeq(S, 1) }
CROSSREFS
KEYWORD
nonn
AUTHOR
Andrew Howroyd, Dec 16 2020
STATUS
approved