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A359397
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Squarefree numbers with weakly decreasing first differences of 0-prepended prime indices.
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3
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1, 2, 3, 5, 6, 7, 11, 13, 15, 17, 19, 21, 23, 29, 30, 31, 35, 37, 41, 43, 47, 53, 55, 59, 61, 65, 67, 71, 73, 77, 79, 83, 89, 91, 97, 101, 103, 105, 107, 109, 113, 119, 127, 131, 133, 137, 139, 143, 149, 151, 157, 163, 167, 173, 179, 181, 187, 191, 193, 197
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OFFSET
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1,2
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COMMENTS
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A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
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LINKS
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FORMULA
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EXAMPLE
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715 has prime indices {3,5,6}, with first differences (2,1), which are weakly decreasing, so 715 is in the sequence.
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MATHEMATICA
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primeMS[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Select[Range[100], SquareFreeQ[#]&&GreaterEqual@@Differences[Prepend[primeMS[#], 0]]&]
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CROSSREFS
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This is the squarefree case of A325362.
These are the sorted Heinz numbers of rows of A359361.
A355536 lists first differences of prime indices, 0-prepended A287352.
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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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