OFFSET
1,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..89 (terms below 10^10)
EXAMPLE
MATHEMATICA
f[n_] := Plus @@ (-(d = Divisors[n])*(-1)^(Range[Length[d], 1, -1])); seq = {}; f1 = f[1]; Do[f2 = f[n]; If[f1 == f2, AppendTo[seq, n-1]]; f1 = f2, {n, 2, 50000}]; seq
SequencePosition[Table[Total[Times@@@Partition[Riffle[Reverse[Divisors[n]], {1, -1}, {2, -1, 2}], 2]], {n, 2565*10^4}], {x_, x_}][[All, 1]] (* Harvey P. Dale, Nov 06 2022 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Mar 13 2020
STATUS
approved