A238792 Number of palindromic partitions of n such that (multiplicity of least part) = 2*(multiplicity of greatest part).
0, 0, 0, 1, 1, 1, 2, 3, 3, 5, 4, 8, 7, 12, 11, 17, 14, 24, 22, 34, 31, 47, 39, 66, 56, 85, 76, 115, 98, 158, 130, 198, 176, 260, 226, 342, 289, 432, 382, 558, 476, 716, 611, 895, 784, 1129, 975, 1430, 1229, 1775, 1551, 2211, 1914, 2756, 2385, 3394, 2964
Offset: 1
Examples
a(10) counts these 5 partitions (written as palindromes): 181, 262, 343, 12421, 113311.
Programs
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Mathematica
z = 40; p[n_] := p[n] = Select[IntegerPartitions[n], (Count[OddQ[Transpose[Tally[#]][[2]]], True] <= 1) && (Count[#, Min[#]] == 2*Count[#, Max[#]]) &]; Table[p[n], {n, 1, 12}] Table[Length[p[n]], {n, 1, z}]
Comments