OFFSET
1,2
COMMENTS
The values of m for which d(k)/d(1) + d(k-1)/d(2) + ... + d(k)/d(1) is an integer are given by A229996. - Clark Kimberling, Jun 16 2018
EXAMPLE
a(2) = 13 = 10/1 + 5/2 + 2/5 + 1/10.
MATHEMATICA
z = 10000; r[n_] := r[n] = Select[Divisors[n], GCD[#, n/#] == 1 &];
k[n_] := f[n] = Length[r[n]]; t[n_] := t[n] = Table[r[n][[k[n] + 1 - i]]/r[n][[k[1] + i - 1]], {i, 1, k[n]}]; s = Table[Plus @@ t[n], {n, 1, z}]; a[n_] := a[n] = If[IntegerQ[s[[n]]], 1, 0]; u = Table[a[n], {n, 1, z}]; v = Flatten[Position[u, 1]] (* A229996 *)
s[[v]] (* A229999 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Oct 31 2013
EXTENSIONS
Definition corrected by Clark Kimberling, Jun 16 2018
STATUS
approved