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A328456
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LCM of the prime indices of 2n + 1, all minus 1; a(0) = 0.
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2
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0, 1, 2, 3, 1, 4, 5, 2, 6, 7, 3, 8, 2, 1, 9, 10, 4, 6, 11, 5, 12, 13, 2, 14, 3, 6, 15, 4, 7, 16, 17, 3, 10, 18, 8, 19, 20, 2, 12, 21, 1, 22, 6, 9, 23, 15, 10, 14, 24, 4, 25, 26, 6, 27, 28, 11, 29, 8, 5, 6, 4, 12, 2, 30, 13, 31, 21, 2, 32, 33, 14, 20, 18, 3, 34
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OFFSET
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0,3
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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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EXAMPLE
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The prime indices of 2 * 17 + 1 = 35, all minus 1, are {2,3}, with LCM 6, so a(17) = 6.
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MATHEMATICA
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Table[If[n==1, 0, LCM@@(PrimePi/@First/@FactorInteger[n]-1)], {n, 1, 100, 2}]
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CROSSREFS
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Positions of records (first appearances) are A006005.
The GCD of the prime indices of n, all minus 1, is A328167(n).
The LCM of the prime indices of n, all plus 1, is A328219(n).
Partitions whose parts minus 1 are relatively prime are A328170.
Numbers whose prime indices minus 1 are relatively prime are A328168.
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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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