A082812 Positions of sign changes in running sum of mu(k)/k: n such that sign(Sum(k=1..n; mu(k)/k)) <> sign(Sum(k=1..n+1; mu(k)/k)).

4, 5, 6, 9, 10, 14, 18, 21, 22, 25, 29, 34, 36, 37, 42, 45, 46, 56, 60, 61, 70, 76, 77, 86, 88, 90, 104, 105, 106, 122, 126, 128, 129, 133, 136, 142, 172, 177, 178, 209, 210, 212, 245, 246, 257, 258, 270, 304, 306, 308, 309, 326, 373, 376, 378, 380, 384, 385, 388, 389

Offset

1,1

Links

Table of n, a(n) for n=1..60.

Example

The running sums of mu(k)/k are 1, 1/2, 1/6, 1/6, -(1/30), 2/15, -(1/105), -(1/105), so the 4th, 5th and 6th terms precede a sign change.

Mathematica

cum=0; res={}; Do[cum += MoebiusMu[k]/k; If[Sign[cum+MoebiusMu[k+1]/(k+1)] =!= Sign[cum], AppendTo[res, k]], {k, 1, 1000}]; res

Crossrefs

Sequence in context: A328173 A223138 A287676 * A255634 A075903 A029942

Adjacent sequences: A082809 A082810 A082811 * A082813 A082814 A082815

Keyword

easy,nonn

Author

Wouter Meeussen, May 24 2003

Status

approved