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A324310
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Numbers k such that s(k) = s(k+1) = s(k+2) where s(k) is the sum of divisors of k that are smaller than sqrt(k) (A070039).
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2
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2, 3, 2505, 64486, 113413, 205365, 423414, 496156, 635053, 664033, 881565, 1011793, 1190685, 1306605, 1442136, 1923655, 1947766, 2286913, 2324422, 2465805, 3030733, 3291553, 3335205, 4100086, 4547353, 4648965, 4987065, 5025705, 5034904, 5069113, 5827485, 5909413
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OFFSET
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1,1
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COMMENTS
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Are there 4 consecutive numbers with the same value of A070039, apart from 2, 3, 4, 5?
The next 4 consecutive numbers with the same value of A070039 start at 1190499411. - Giovanni Resta, Sep 05 2019
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LINKS
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Table of n, a(n) for n=1..32.
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EXAMPLE
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2 is in the sequence since A070039(2) = A070039(3) = A070039(4) = 1.
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MATHEMATICA
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s[n_] := DivisorSum[n, # &, # < Sqrt[n] &]; seq={}; s1 = 0; s2=0; Do[s3 = s[n]; If[s1 == s2 && s2 == s3, AppendTo[seq, n - 2]]; s1 = s2; s2 = s3, {n, 2, 10^5}]; seq
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CROSSREFS
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Cf. A070039, A324295, A325175.
Sequence in context: A288171 A137321 A066848 * A125612 A185156 A235935
Adjacent sequences: A324307 A324308 A324309 * A324311 A324312 A324313
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KEYWORD
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nonn
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AUTHOR
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Amiram Eldar, Sep 03 2019
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STATUS
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approved
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