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A070546
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a(n) = Card( k, 0<k<=n such that k is relatively prime to tau(k)=A000005(k)).
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1
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1, 1, 2, 3, 4, 4, 5, 5, 5, 5, 6, 6, 7, 7, 8, 9, 10, 10, 11, 11, 12, 12, 13, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, 23, 23, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 28, 28, 29, 29, 30, 30, 31, 31, 31, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37
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OFFSET
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1,3
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LINKS
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MATHEMATICA
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Accumulate[Table[Boole[CoprimeQ[n, DivisorSigma[0, n]]], {n, 1, 100}]] (* Amiram Eldar, Apr 30 2022 *)
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PROG
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(PARI) for(n=1, 100, print1(sum(i=1, n, if(gcd(i, numdiv(i))-1, 0, 1)), ", "))
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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