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0, 1, 2, 2, 3, 2, 4, 2, 4, 3, 5, 2, 6, 2, 4, 4, 7, 2, 8, 2, 6, 4, 9, 2, 6, 4, 4, 4, 10, 4, 11, 2, 4, 4, 6, 4, 12, 2, 8, 4, 13, 2, 14, 2, 4, 8, 15, 2, 8, 3, 8, 2, 16, 2, 9, 2, 8, 6, 17, 2, 18, 4, 4, 6, 6, 4, 19, 4, 4, 2, 20, 4, 21, 4, 4, 4, 8, 4, 22, 2, 8, 4, 23, 6, 12, 8, 16, 8, 24, 6, 12, 4, 12, 12, 12, 4, 25, 3, 8, 4, 26, 6, 27, 2, 8
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OFFSET
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1,3
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COMMENTS
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If a(n) is odd, then A067029(n) = 1 (and A319710(n) = 0), but not necessarily vice versa. See also formulas in A106737.
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LINKS
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FORMULA
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MATHEMATICA
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Array[If[# == 1, 0, DivisorSigma[0, #] &@ Floor@ Total@ Flatten@ MapIndexed[#1 2^(#2 - 1) &, Flatten[Table[2^(PrimePi@ #1 - 1), {#2}] & @@@ FactorInteger@ #]]] &, 105] (* Michael De Vlieger, Mar 11 2019 *)
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PROG
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(PARI)
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)};
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CROSSREFS
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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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