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A348936
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Numbers k congruent to 1 or 5 mod 6, for which A064989(A064989(sigma(k^2))) > A064989(A064989(k^2)), where A064989 shifts the prime factorization one step towards lower primes, and sigma is the sum of divisors function.
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3
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5, 7, 11, 13, 17, 25, 29, 35, 41, 49, 55, 59, 65, 71, 77, 85, 89, 91, 95, 101, 115, 119, 121, 125, 131, 143, 145, 155, 161, 167, 169, 173, 175, 185, 187, 203, 205, 209, 215, 221, 227, 235, 245, 253, 265, 275, 287, 289, 293, 295, 305, 319, 323, 325, 329, 343, 355, 361, 365, 377, 383, 385, 391, 413, 415, 425, 445, 451
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OFFSET
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1,1
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COMMENTS
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Square roots of squares present in A348754.
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LINKS
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MATHEMATICA
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f[2, e_] := 1; f[p_, e_] := NextPrime[p, -1]^e; s[1] = 1; s[n_] := Times @@ f @@@ FactorInteger[n]; Select[Range[450], MemberQ[{1, 5}, Mod[#, 6]] && s[s[DivisorSigma[1, #^2]]] > s[s[#^2]] &] (* Amiram Eldar, Nov 04 2021 *)
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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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