OFFSET
1,9
FORMULA
a(1) = 1; a(n) = Sum_{d|n, n/d > 2} a(d).
EXAMPLE
a(12) = 3: 12 = 3*4 = 4*3.
MATHEMATICA
a[n_] := a[n] = If[n == 1, n, Sum[If[n/d > 2, a[d], 0], {d, Divisors[n]}]]; Table[a[n], {n, 1, 87}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Mar 15 2024
STATUS
approved