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A332270
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Numbers k such that Sum_{j=1..k} j*floor(k/j) is divisible by k+1.
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0
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3, 4, 14, 29, 82, 67117, 86249, 140064, 185699, 392081, 2915083, 6315155, 9723681, 17754993, 820165642, 9388829301, 143904506919, 192738887697
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OFFSET
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1,1
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COMMENTS
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LINKS
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MATHEMATICA
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q[n_] := Divisible[Sum[j * Floor[n/j], {j, 1, n}], n + 1]; Select[Range[100], q] (* Amiram Eldar, May 03 2021 *)
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PROG
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(PARI) for(k=1, 1e4, if(sum(j=1, k, k\j*j)%(k+1)==0, print1(k", ")))
(PARI) s=0; for(k=1, 1e7, s+=sigma(k); if(s%(k+1)==0, print1(k", ")))
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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