OFFSET
1,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 1..1000
MATHEMATICA
t[n_, k_] := If[Divisible[n, k], MoebiusMu[n/k], 0] - If[Divisible[n, k + 1], MoebiusMu[n/(k + 1)], 0]; Table[Sum[Abs[t[n, k]], {k, 1, n}], {n, 1, 50}] (* G. C. Greubel, Oct 26 2017 *)
PROG
(PARI) {a(n)=local(M=matrix(n, n, r, c, if(r>=c, floor(r/c)))^-1); sum(k=1, n, abs(M[n, k]))}
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Oct 09 2006
STATUS
approved