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A082926
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Difference between the number of primes equal to or less than n and (1 + the number of nonsquarefree numbers equal to or less than n).
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2
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1, 0, 1, 0, 1, 1, 2, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 1, 2, 3, 2, 2, 1, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 2, 1, 2, 3, 3, 2, 3, 4, 5, 5, 6, 5, 6, 6, 7, 7, 7, 6, 7, 6, 6, 7, 8, 8, 8, 7, 8, 8, 8, 7, 8, 7, 7, 8, 9, 9, 9, 8, 9, 10, 10, 9, 10, 10, 10, 10, 11, 10, 11, 11, 12, 12, 12, 12, 13, 12
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OFFSET
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1,7
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LINKS
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FORMULA
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MATHEMATICA
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nsfQ[n_] := n == 1 || ! SquareFreeQ[n]; Abs[Accumulate[Table[If[nsfQ[n], 1, 0] - If[PrimeQ[n], 1, 0], {n, 1, 100}]]] (* Amiram Eldar, Jun 13 2022 *)
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PROG
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(PARI) a(n) = abs(sum(k=1, n, !issquarefree(k)) + 1 - primepi(n)); \\ Michel Marcus, Mar 27 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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Anonymous, Apr 15 2003
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EXTENSIONS
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STATUS
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approved
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