%I A120421
%S A120421 1,2,3,6,10,20,36,72,135,272,528,1052,2080,4160,8244,16508,32896,65768
%N A120421 Number of distinct ribbon Schur functions with n boxes; also the number 
               of distinct multisets of partitions determined by all coarsenings 
               of compositions of n.
%D A120421 Louis Billera, Hugh Thomas and Stephanie van Willigenburg "Decomposable 
               compositions, symmetric quasisymmetric functions and equality of 
               ribbon Schur functions" Adv. Math. 204: 204-240 (2006).
%H A120421 Louis Billera, Hugh Thomas and Stephanie van Willigenburg <a href="http:/
               /arXiv.org/abs/math.CO/0405434">"Decomposable compositions, symmetric 
               quasisymmetric functions and equality of ribbon Schur functions"</
               a> Adv. Math. 204: 204-240 (2006).
%e A120421 a(4)=6 as the multisets are {4}, {4,31}, {4,22}, {4,31,22,211}, {4,31,
               31,211} and {4,31,31,22,211,211,211,1111}
%Y A120421 Cf. A005418.
%Y A120421 Sequence in context: A008927 A052525 A006606 this_sequence A005418 A002215 
               A007562
%Y A120421 Adjacent sequences: A120418 A120419 A120420 this_sequence A120422 A120423 
               A120424
%K A120421 nonn
%O A120421 1,2
%A A120421 Stephanie van Willigenburg (steph(AT)math.ubc.ca), Jul 09 2006