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A325199 Number of integer partitions of n such that the difference between the length of the minimal triangular partition containing and the maximal triangular partition contained in the Young diagram is 2. 5

%I #14 Apr 23 2019 11:14:48

%S 0,0,0,2,0,2,6,3,2,9,15,12,6,12,27,38,34,22,20,43,74,94,90,67,48,69,

%T 130,194,232,230,187,132,129,218,364,497,576,578,498,367,290,378,642,

%U 977,1264,1435,1448,1290,1000,735,728

%N Number of integer partitions of n such that the difference between the length of the minimal triangular partition containing and the maximal triangular partition contained in the Young diagram is 2.

%C The Heinz numbers of these partitions are given by A325197.

%H FindStat, <a href="http://www.findstat.org/StatisticsDatabase/St000384">St000384: The maximal part of the shifted composition of an integer partition</a>

%H FindStat, <a href="http://www.findstat.org/StatisticsDatabase/St000783">St000783: The maximal number of occurrences of a colour in a proper colouring of a Ferrers diagram</a>

%e The a(3) = 2 through a(10) = 15 partitions (empty columns not shown):

%e (3) (41) (33) (43) (521) (333) (433)

%e (111) (2111) (42) (2221) (32111) (441) (442)

%e (222) (4111) (522) (532)

%e (411) (531) (541)

%e (2211) (3222) (3322)

%e (3111) (5211) (3331)

%e (32211) (4222)

%e (33111) (4411)

%e (42111) (5221)

%e (5311)

%e (32221)

%e (33211)

%e (42211)

%e (43111)

%e (52111)

%t otb[ptn_]:=Min@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];

%t otbmax[ptn_]:=Max@@MapIndexed[#1+#2[[1]]-1&,Append[ptn,0]];

%t Table[Length[Select[IntegerPartitions[n],otbmax[#]-otb[#]==2&]],{n,0,30}]

%Y Column k=2 of A325200.

%Y Cf. A046660, A065770, A071724, A243055, A325166, A325169, A325178, A325188, A325189, A325191, A325195, A325197, A325198.

%K nonn,look

%O 0,4

%A _Gus Wiseman_, Apr 11 2019

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