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A339875
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Intersection of A137409 and A339870: Composite numbers k of the form 4u+1 having more than one prime factor of type 4u+3, and for which the odd part of phi(k) divides k-1.
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2
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561, 6601, 8481, 17733, 23001, 30889, 54741, 62745, 88561, 106141, 319965, 359601, 449065, 534061, 609301, 949785, 1357621, 2162721, 2288661, 2615977, 3284281, 4005001, 4698001, 4830805, 5381265, 6313681, 6594721, 6840001, 8093701, 11782005, 11921001, 14665105, 14892153, 15217741, 16577785, 19683001, 20154061, 20441701
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OFFSET
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1,1
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COMMENTS
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Composite numbers k of the form 4u+1 for which the odd part of phi(k) divides k-1 and for which A065338(k) > 1.
All terms k are squarefree and the 3-adic valuation of A065338(k) is a nonzero even number.
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LINKS
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PROG
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(PARI)
A065338(n) = { my(f = factor(n)); for (i=1, #f~, f[i, 1] = (f[i, 1]%4)); factorback(f); };
isA339870(n) = ((n>1)&&!isprime(n)&&(1==(n%4))&&!((n-1)%A000265(eulerphi(n))));
isA339875(n) = (isA137409(n)&&isA339870(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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