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A343983
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Numbers k such that Sum_{j|k} j^j == 1 (mod k).
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3
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1, 2, 3, 4, 5, 7, 9, 11, 13, 17, 19, 23, 25, 27, 29, 31, 37, 41, 43, 47, 49, 53, 59, 61, 67, 71, 72, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 121, 125, 127, 131, 137, 139, 149, 151, 157, 163, 167, 169, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257
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OFFSET
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1,2
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COMMENTS
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This sequence is different from A074583.
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LINKS
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MATHEMATICA
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q[n_] := Divisible[DivisorSum[n, #^# &] - 1, n]; Select[Range[260], q] (* Amiram Eldar, May 06 2021 *)
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PROG
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(PARI) isok(n) = sumdiv(n, d, Mod(d, n)^d)==1;
(Python)
from itertools import count, islice
from sympy import divisors
def A343983_gen(): # generator of terms
yield 1
for k in count(1):
if sum(pow(j, j, k) for j in divisors(k, generator=True)) % k == 1:
yield k
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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