OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..10000
FORMULA
a(n) = min { k : A167865(k) = n }.
EXAMPLE
MAPLE
with(numtheory):
a:= proc() local t, a, b;
t:= -1;
a:= proc() -1 end;
b:= proc(n) option remember;
`if`(n=0, 1, add(b((n-d)/d), d=divisors(n) minus{1}))
end:
proc(n) local h;
while a(n) = -1 do
t:= t+1;
h:= b(t);
if a(h) = -1 then a(h):= t fi
od; a(n)
end
end():
seq(a(n), n=0..100);
MATHEMATICA
a[n0_] := Module[{t = -1, a, b}, a[_] = -1; b[n_] := b[n] = If[n == 0, 1, Sum[b[(n - d)/d], {d, Divisors[n] ~Complement~ {1}}]]; While[a[n] == -1, t++; h = b[t]; If[a[h] == -1, a[h] = t]]; a[n0]];
Table[a[n], {n, 0, 100}] (* Jean-François Alcover, May 21 2018, translated from Maple *)
CROSSREFS
KEYWORD
nonn,look
AUTHOR
Alois P. Heinz, Mar 28 2011
STATUS
approved