A067195 Numbers n such that M(n) = Sum_{i=1..n} mu(sigma(i)) where M(n) is the Mertens function A002321(n).

1, 2, 4, 30, 33, 38, 42, 45, 47, 48, 57, 59, 60, 64, 66, 69, 77, 82, 85, 104, 106, 118, 121, 194, 196, 201, 285, 287, 288, 290, 465, 467, 468, 470, 499, 500, 510, 610, 614, 626, 628, 631, 632, 642, 718, 723, 724, 785, 793, 798, 811, 812, 814, 823, 824, 825, 838

Offset: 1

Author

Benoit Cloitre, Feb 19 2002

Keywords

• nonn

Links

• Indranil Ghosh, Table of n, a(n) for n = 1..263 (terms < 5000)

Crossrefs

Cf. A000203, A008683.

Programs

Mathematica

M[n_] := Sum[MoebiusMu[k], {k, n}]; Select[Range@ 838, Sum[MoebiusMu[DivisorSigma[1, i]], {i, #}] == M[#] &] (* Indranil Ghosh, Mar 16 2017 *)

PARI

isok(n) = sum(i = 1, n, moebius(sigma(i))) == mertens(n); \\ Michel Marcus, Sep 24 2013