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A303996 Numbers whose sum of divisors is the sixth power of one of their divisors. 6
1, 17490, 19410, 22578, 2823492, 162523452, 165982908, 216731788, 221416468, 221940628, 226768440, 230365560, 232815480, 234896520, 238942920, 240737160, 241362120, 242067720, 242454120, 242655720, 258182910, 264254670, 268298190, 272819070, 277297710, 286008510 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Subset of A019424.
LINKS
EXAMPLE
Divisors of 17490 are 1, 2, 3, 5, 6, 10, 11, 15, 22, 30, 33, 53, 55, 66, 106, 110, 159, 165, 265, 318, 330, 530, 583, 795, 1166, 1590, 1749, 2915, 3498, 5830, 8745, 17490 and their sum is 46656 = 6^6.
MAPLE
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]^6 then print(n); break; fi; od; od; end: P(10^9);
PROG
(PARI) isok(n) = (n==1) || (ispower(s=sigma(n), 6) && !(n % sqrtnint(s, 6))); \\ Michel Marcus, May 05 2018
CROSSREFS
Sequence in context: A043875 A236806 A048256 * A251641 A251638 A234562
KEYWORD
nonn,easy
AUTHOR
Paolo P. Lava, May 04 2018
STATUS
approved

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Last modified May 27 03:56 EDT 2024. Contains 372847 sequences. (Running on oeis4.)