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A325695 Number of length-3 strict integer partitions of n such that the largest part is not the sum of the other two. 4

%I #10 Jun 18 2020 19:38:48

%S 0,0,0,0,0,0,0,1,1,3,2,5,5,8,7,12,11,16,15,21,20,27,25,33,32,40,38,48,

%T 46,56,54,65,63,75,72,85,83,96,93,108,105,120,117,133,130,147,143,161,

%U 158,176,172,192,188,208,204,225,221,243,238,261,257,280,275

%N Number of length-3 strict integer partitions of n such that the largest part is not the sum of the other two.

%F Conjectures from _Colin Barker_, May 15 2019: (Start)

%F G.f.: x^7*(1 + x + 2*x^2) / ((1 - x)^3*(1 + x)^2*(1 + x^2)*(1 + x + x^2)).

%F a(n) = a(n-2) + a(n-3) + a(n-4) - a(n-5) - a(n-6) - a(n-7) + a(n-9) for n>9.

%F (End)

%F a(n) = A325696(n)/6. - _Alois P. Heinz_, Jun 18 2020

%e The a(7) = 1 through a(15) = 12 partitions (A = 10, B = 11, C = 12):

%e (421) (521) (432) (631) (542) (543) (643) (653) (654)

%e (531) (721) (632) (732) (652) (842) (753)

%e (621) (641) (741) (742) (851) (762)

%e (731) (831) (751) (932) (843)

%e (821) (921) (832) (941) (852)

%e (841) (A31) (861)

%e (931) (B21) (942)

%e (A21) (951)

%e (A32)

%e (A41)

%e (B31)

%e (C21)

%t Table[Length[Select[IntegerPartitions[n,{3}],UnsameQ@@#&&#[[1]]!=#[[2]]+#[[3]]&]],{n,0,30}]

%Y Cf. A000041, A001399, A005044, A008642, A069905, A124278.

%Y Cf. A325686, A325690, A325691, A325694, A325696.

%K nonn

%O 0,10

%A _Gus Wiseman_, May 15 2019

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