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A078544
Non-balanced numbers in A015761.
8
38, 54, 87, 95, 114, 126, 135, 147, 174, 182, 209, 215, 216, 222, 258, 285, 294, 297, 315, 430, 455, 456, 540, 546, 551, 609, 627, 632, 635, 645, 762, 783, 836, 899, 957, 1015, 1032, 1102, 1107, 1118, 1140, 1188, 1211, 1218, 1270, 1290, 1330, 1343, 1349
OFFSET
1,1
LINKS
FORMULA
Mod[sigma[3, a(n)], phi[a(n)]]=0; Mod[sigma[1, a(n)], phi[a(n)]]><0.
MATHEMATICA
Select[Range[1350], Divisible[DivisorSigma[3, #], (phi = EulerPhi[#])] && !Divisible[DivisorSigma[1, #], phi] &] (* Amiram Eldar, Jun 23 2019 *)
PROG
(PARI) isok(k) = my(phi=eulerphi(k)); ((sigma(k, 3) % phi) == 0) && (sigma(k) % phi); \\ Michel Marcus, Jun 23 2019
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Dec 05 2002
STATUS
approved