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A339818
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Carmichael numbers k for which the 2-adic valuation of phi(k) does not exceed the 2-adic valuation of k-1.
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5
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1729, 15841, 3057601, 3828001, 5310721, 8355841, 8830801, 9439201, 14676481, 15829633, 17236801, 40280065, 78091201, 83099521, 84350561, 92625121, 94536001, 104852881, 118901521, 129762001, 157731841, 163954561, 180115489, 193708801, 214852609, 221884001, 279377281, 382304161, 382536001, 438359041, 481239361, 511338241
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OFFSET
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1,1
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LINKS
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MATHEMATICA
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carmichaels = Cases[Import["https://oeis.org/A002997/b002997.txt", "Table"], {_, _}][[;; , 2]]; q[n_] := IntegerExponent[EulerPhi[n], 2] <= IntegerExponent[n - 1, 2]; Select[carmichaels, q] (* Amiram Eldar, Dec 26 2020 *)
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PROG
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(PARI)
isA339818(n) = ((n>1)&&issquarefree(n)&&!isprime(n)&&(valuation(eulerphi(n), 2)<=valuation(n-1, 2))&&(0==((n-1)%A002322(n))));
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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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