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A362621
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One and numbers whose multiset of prime factors (with multiplicity) has the same median as maximum.
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10
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1, 2, 3, 4, 5, 7, 8, 9, 11, 13, 16, 17, 18, 19, 23, 25, 27, 29, 31, 32, 37, 41, 43, 47, 49, 50, 53, 54, 59, 61, 64, 67, 71, 73, 75, 79, 81, 83, 89, 97, 98, 101, 103, 107, 108, 109, 113, 121, 125, 127, 128, 131, 137, 139, 147, 149, 151, 157, 162, 163, 167, 169
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OFFSET
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1,2
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COMMENTS
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First differs from A334965 in having 750 and lacking 2250.
The median of a multiset is either the middle part (for odd length), or the average of the two middle parts (for even length).
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LINKS
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EXAMPLE
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The prime factorization of 108 is 2*2*3*3*3, and the multiset {2,2,3,3,3} has median 3 and maximum 3, so 108 is in the sequence.
The prime factorization of 2250 is 2*3*3*5*5*5, and the multiset {2,3,3,5,5,5} has median 4 and maximum 5, so 2250 is not in the sequence.
The terms together with their prime indices begin:
1: {} 25: {3,3} 64: {1,1,1,1,1,1}
2: {1} 27: {2,2,2} 67: {19}
3: {2} 29: {10} 71: {20}
4: {1,1} 31: {11} 73: {21}
5: {3} 32: {1,1,1,1,1} 75: {2,3,3}
7: {4} 37: {12} 79: {22}
8: {1,1,1} 41: {13} 81: {2,2,2,2}
9: {2,2} 43: {14} 83: {23}
11: {5} 47: {15} 89: {24}
13: {6} 49: {4,4} 97: {25}
16: {1,1,1,1} 50: {1,3,3} 98: {1,4,4}
17: {7} 53: {16} 101: {26}
18: {1,2,2} 54: {1,2,2,2} 103: {27}
19: {8} 59: {17} 107: {28}
23: {9} 61: {18} 108: {1,1,2,2,2}
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MATHEMATICA
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Select[Range[100], (y=Flatten[Apply[ConstantArray, FactorInteger[#], {1}]]; Max@@y==Median[y])&]
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CROSSREFS
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Partitions of this type are counted by A053263.
For parts at middle position (instead of median) we have A362622.
A362611 counts modes in prime factorization, triangle version A362614.
A362613 counts co-modes in prime factorization, triangle version A362615.
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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