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A343931
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Numbers k such that Sum_{j=1..k} (-j)^j == 0 (mod k).
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2
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1, 3, 4, 11, 131, 188, 324, 445, 3548, 8284, 201403, 253731, 564084, 1812500, 4599115
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OFFSET
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1,2
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COMMENTS
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Also numbers k such that k divides A001099(k).
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LINKS
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MATHEMATICA
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q[n_] := Divisible[Sum[PowerMod[-k, k, n], {k, 1, n}], n]; Select[Range[8500], q] (* Amiram Eldar, May 04 2021 *)
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PROG
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(PARI) isok(n) = sum(k=1, n, Mod(-k, n)^k)==0;
(Python)
from itertools import accumulate, count, islice
def A343931_gen(): # generator of terms
yield 1
for i, j in enumerate(accumulate((-k)**k for k in count(1)), start=2):
if j % i == 0:
yield i
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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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