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A015734
Odd numbers k such that d(k) does not divide phi(k).
2
25, 27, 75, 81, 121, 189, 225, 275, 289, 297, 343, 363, 405, 425, 513, 529, 567, 575, 605, 621, 725, 729, 825, 837, 841, 867, 1025, 1029, 1053, 1089, 1161, 1175, 1225, 1269, 1275, 1325, 1331, 1377, 1445, 1475, 1539, 1587, 1593, 1681, 1725
OFFSET
1,1
LINKS
MATHEMATICA
Select[Range[1, 2000, 2], !Divisible[EulerPhi[#], DivisorSigma[0, #]] &] (* Amiram Eldar, May 15 2024 *)
PROG
(PARI) is(k) = if(k%2, my(f = factor(k), d = numdiv(f), p = eulerphi(f)); p % d, 0); \\ Amiram Eldar, May 15 2024
CROSSREFS
Intersection of A005408 and A015733.
Cf. A000005 (d), A000010 (phi).
Sequence in context: A129820 A096522 A195351 * A221617 A083806 A239521
KEYWORD
nonn
EXTENSIONS
Offset corrected by Amiram Eldar, May 15 2024
STATUS
approved