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A325337
Numbers whose prime exponents are distinct and cover an initial interval of positive integers.
18
1, 2, 3, 5, 7, 11, 12, 13, 17, 18, 19, 20, 23, 28, 29, 31, 37, 41, 43, 44, 45, 47, 50, 52, 53, 59, 61, 63, 67, 68, 71, 73, 75, 76, 79, 83, 89, 92, 97, 98, 99, 101, 103, 107, 109, 113, 116, 117, 124, 127, 131, 137, 139, 147, 148, 149, 151, 153, 157, 163, 164
OFFSET
1,2
COMMENTS
The Heinz number of an integer partition (y_1,...,y_k) is prime(y_1)*...*prime(y_k), so these are Heinz numbers of integer partitions with distinct multiplicities covering an initial interval of positive integers. The enumeration of these partitions by sum is given by A320348.
EXAMPLE
The sequence of terms together with their prime indices begins:
1: {}
2: {1}
3: {2}
5: {3}
7: {4}
11: {5}
12: {1,1,2}
13: {6}
17: {7}
18: {1,2,2}
19: {8}
20: {1,1,3}
23: {9}
28: {1,1,4}
29: {10}
31: {11}
37: {12}
41: {13}
43: {14}
44: {1,1,5}
MATHEMATICA
normQ[m_]:=Or[m=={}, Union[m]==Range[Max[m]]];
Select[Range[100], UnsameQ@@Last/@FactorInteger[#]&&normQ[Last/@FactorInteger[#]]&]
KEYWORD
nonn
AUTHOR
Gus Wiseman, May 01 2019
STATUS
approved