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A372437
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(Least binary index of n) minus (least prime index of n).
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13
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1, -1, 2, -2, 1, -3, 3, -1, 1, -4, 2, -5, 1, -1, 4, -6, 1, -7, 2, -1, 1, -8, 3, -2, 1, -1, 2, -9, 1, -10, 5, -1, 1, -2, 2, -11, 1, -1, 3, -12, 1, -13, 2, -1, 1, -14, 4, -3, 1, -1, 2, -15, 1, -2, 3, -1, 1, -16, 2, -17, 1, -1, 6, -2, 1, -18, 2, -1, 1, -19, 3
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OFFSET
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2,3
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COMMENTS
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A binary index of n is any position of a 1 in its reversed binary expansion. The binary indices of n are row n of A048793.
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.
Is 0 the only integer not appearing in the data?
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LINKS
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FORMULA
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MATHEMATICA
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bix[n_]:=Join@@Position[Reverse[IntegerDigits[n, 2]], 1];
prix[n_]:=If[n==1, {}, Flatten[Cases[FactorInteger[n], {p_, k_}:>Table[PrimePi[p], {k}]]]];
Table[Min[bix[n]]-Min[prix[n]], {n, 2, 100}]
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CROSSREFS
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Positions of first appearances are A174090.
A003963 gives product of prime indices.
A070939 gives length of binary expansion.
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KEYWORD
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sign,base
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AUTHOR
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STATUS
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approved
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