A078549 Non-balanced numbers in A015771.

749, 1498, 2247, 2568, 2889, 2996, 3745, 3959, 4494, 5778, 5992, 6741, 7490, 7918, 8876, 8988, 9416, 9737, 9994, 11235, 11556, 11877, 11984, 12733, 13482, 14231, 14445, 14980, 16264, 17976, 18404, 19474, 20223, 20804, 22363, 22470, 23112

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Formula

sigma_13(a(n)) mod phi(a(n)) = 0; sigma(a(n)) mod phi(a(n)) <> 0.

Mathematica

q[n_] := Sign[Mod[DivisorSigma[{1, 13}, n], EulerPhi[n]]] == {1, 0}; Select[Range[24000], q] (* Amiram Eldar, Apr 11 2024 *)

Prog

(PARI) is(n) = {my(f = factor(n), phi = eulerphi(f)); (sigma(f) % phi) && !(sigma(f, 13) % phi); } \\ Amiram Eldar, Apr 11 2024

Crossrefs

Cf. A000010, A000203, A013961, A015771, A020492, A078539.

Cf. A074866, A074868, A077801, A077803, A078544, A078550.

Sequence in context: A184024 A263381 A071924 * A252524 A252525 A252681

Adjacent sequences: A078546 A078547 A078548 * A078550 A078551 A078552

Keyword

nonn

Author

Labos Elemer, Dec 05 2002

Status

approved