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A276031 Number of edges in the graded poset of the partitions of n taken modulo 3, where a partition into k parts is joined to a partition into k+1 parts if the latter is a refinement of the former. 1

%I

%S 0,1,2,5,9,14,21,30,41,54,70,89,110,135,164,195,231,272,315,364,419,

%T 476,540,611,684,765,854,945,1045,1154,1265,1386,1517,1650,1794,1949,

%U 2106,2275,2456,2639,2835,3044,3255,3480,3719,3960,4216,4487,4760,5049,5354

%N Number of edges in the graded poset of the partitions of n taken modulo 3, where a partition into k parts is joined to a partition into k+1 parts if the latter is a refinement of the former.

%H Alois P. Heinz, <a href="/A276031/b276031.txt">Table of n, a(n) for n = 1..10000</a>

%F G.f.: (x^6-2*x^5+x^4-x^3+2*x^2+1)*x^2/((x^2+x+1)^2*(x-1)^4). - _Alois P. Heinz_, Aug 27 2016

%e a(6) = 14, the 14 edges are: (111111) - (21111), (21111) - (1110), (21111) - (2211), (1110) - (111), (1110) - (210), (2211) - (111), (2211) - (210), (2211) - (222), (210) - (00), (210) - (21), (111) - (21), (222) - (21), (00) - (0), (21) - (0).

%Y Cf. A000097, A140144.

%K nonn

%O 1,3

%A _Caleb Ji_, Aug 17 2016

%E More terms from _Alois P. Heinz_, Aug 27 2016

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Last modified May 26 13:17 EDT 2022. Contains 354092 sequences. (Running on oeis4.)