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A354715
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Numbers k such that the number of divisors of k divides k-2.
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7
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1, 2, 6, 10, 14, 20, 22, 26, 32, 34, 38, 42, 44, 46, 50, 58, 62, 66, 68, 74, 82, 86, 92, 94, 98, 106, 112, 114, 116, 118, 122, 130, 134, 138, 142, 146, 154, 158, 162, 164, 166, 170, 178, 186, 188, 194, 202, 206, 210, 212, 214, 218, 226, 236, 242, 250, 254, 258, 262, 266, 272, 274, 278, 282
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OFFSET
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1,2
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COMMENTS
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Numbers k such that k == 2 (mod A000005(k)).
Odd terms are squares. Next odd term after 1 is 5^16 * 29^6 = 90762835845947265625 (cf. A354716).
The smallest even square is 2^16 * 5^6 = 1024000000. - Jianing Song, Jun 04 2022
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LINKS
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MATHEMATICA
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Select[Range[300], Divisible[# - 2, DivisorSigma[0, #]] &] (* Amiram Eldar, Jun 03 2022 *)
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PROG
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(PARI) isA354715(k) = (Mod(k, numdiv(k)) == 2) \\ Jianing Song, Jun 04 2022
(Python)
from sympy import divisor_count
def ok(n): return n > 0 and (n-2)%divisor_count(n) == 0
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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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