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 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. 0
 1, 2, 3, 6, 10, 20, 36, 72, 135, 272, 528, 1052, 2080, 4160, 8244, 16508, 32896, 65770, 131328, 262632, 524744, 1049600, 2098176, 4196200, 8390620, 16781312, 33558291, 67116944, 134225920, 268451240, 536887296, 1073774376, 2147515424 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 REFERENCES 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). LINKS 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). M. Rubey, The number of ribbon Schur functions [From Martin Rubey (martin.rubey(AT)math.uni-hannover.de), Aug 17 2010] FORMULA Dirichlet G.f.: 2 C(s) S(s)/(C(s)+S(s)) where C(s)=Sum_{n>0} 2^{n-1} n^{-s} and S(s)=Sum_{n>0} 2^{floor(n/2)} n^{-s} [From Martin Rubey (martin.rubey(AT)math.uni-hannover.de), Aug 17 2010] EXAMPLE 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} CROSSREFS Cf. A005418. Sequence in context: A331488 A052525 A006606 * A005418 A329699 A002215 Adjacent sequences: A120418 A120419 A120420 * A120422 A120423 A120424 KEYWORD nonn AUTHOR Stephanie van Willigenburg (steph(AT)math.ubc.ca), Jul 09 2006 EXTENSIONS Corrected and extended by Martin Rubey (martin.rubey(AT)math.uni-hannover.de), Aug 17 2010 STATUS approved

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Last modified February 5 19:45 EST 2023. Contains 360087 sequences. (Running on oeis4.)