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A303994
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Numbers whose sum of divisors is the fourth power of one of their divisors.
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7
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1, 510, 642, 3394440, 3629640, 3653640, 3663240, 3673080, 3701160, 3736920, 3901080, 3958680, 4077960, 4137240, 4240920, 4251480, 4256520, 4273320, 4274520, 4319880, 7300854, 12798240, 13362720, 14405664, 15170820, 16173024, 16342368, 16354884, 16361184, 16957668, 17113404
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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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Divisors of 510 are 1, 2, 3, 5, 6, 10, 15, 17, 30, 34, 51, 85, 102, 170, 255, 510 and their sum is 1296 = 6^4.
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MAPLE
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with(numtheory): P:=proc(q) local a, k, n;
for n from 1 to q do a:=sort([op(divisors(n))]);
for k from 1 to nops(a) do if sigma(n)=a[k]^4 then print(n); break; fi; od; od; end: P(10^9);
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MATHEMATICA
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Select[Range[17114000], MemberQ[Divisors[#]^4, DivisorSigma[1, #]]&] (* Harvey P. Dale, Jul 22 2021 *)
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PROG
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(PARI) isok(n) = (n==1) || (ispower(s=sigma(n), 4) && !(n % sqrtnint(s, 4))); \\ Michel Marcus, May 05 2018
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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