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A229207
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Numbers k such that Sum_{j=1..k} tau(j)^j == 0 (mod k), where tau(j) = A000005(j), the number of divisors of j.
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5
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1, 46, 135, 600, 1165, 1649, 5733, 6788, 6828, 9734, 29686, 363141, 1542049
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OFFSET
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1,2
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COMMENTS
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LINKS
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EXAMPLE
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tau(1)^1 + tau(2)^2 + ... + tau(45)^45 + tau(46)^46 = 1^1 + 2^2 + ... + 6^45 + 4^46 = 86543618042218910328339719795268200166 and 86543618042218910328339719795268200166 / 46 = 1881383000917802398442167821636265221.
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MAPLE
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with(numtheory); P:=proc(q) local n, t; t:=0;
for n from 1 to q do t:=t+tau(n)^n; if t mod n=0 then print(n);
fi; od; end: P(10^6);
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MATHEMATICA
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Module[{nn=30000, ac}, ac=Accumulate[Table[DivisorSigma[0, i]^i, {i, nn}]]; Select[ Thread[{ac, Range[nn]}], Divisible[#[[1]], #[[2]]]&]][[All, 2]](* Harvey P. Dale, Dec 13 2018 *)
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PROG
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(PARI) isok(n) = sum(i=1, n, Mod(numdiv(i), n)^i) == 0; \\ Michel Marcus, Feb 25 2016
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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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