cp's OEIS Frontend

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.

%I A276031 #20 Sep 06 2018 22:16:02
%S A276031 0,1,2,5,9,14,21,30,41,54,70,89,110,135,164,195,231,272,315,364,419,
%T A276031 476,540,611,684,765,854,945,1045,1154,1265,1386,1517,1650,1794,1949,
%U A276031 2106,2275,2456,2639,2835,3044,3255,3480,3719,3960,4216,4487,4760,5049,5354
%N 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.
%H A276031 Alois P. Heinz, <a href="/A276031/b276031.txt">Table of n, a(n) for n = 1..10000</a>
%F A276031 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 A276031 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 A276031 Cf. A000097, A140144.
%K A276031 nonn
%O A276031 1,3
%A A276031 _Caleb Ji_, Aug 17 2016
%E A276031 More terms from _Alois P. Heinz_, Aug 27 2016