OFFSET
0,2
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..18
EXAMPLE
a(1) = 4 since 4 is the least number that has 2^1 = 2 squarefree divisors (1 and 2) and 2 powerful divisors (1 and 4).
a(2) = 36 since 36 is the least number that has 2^2 = 4 squarefree divisors (1, 2, 3 and 6) and 4 powerful divisors (1, 4, 9 and 36).
MATHEMATICA
f1[p_, e_] := 2; s1[1] = 1; s1[n_] := Times @@ f1 @@@ FactorInteger[n]; f2[p_, e_] := e; s2[1] = 1; s2[n_] := Times @@ f2 @@@ FactorInteger[n]; v = Cases[Import["https://oeis.org/A025487/b025487.txt", "Table"], {_, _}][[;; , 2]]; With[{m = 9}, seq = Table[0, {m}]; Do[If[(s = s1[v[[k]]]) == s2[v[[k]]], e = IntegerExponent[s, 2] + 1; If[e <= m && seq[[e]] == 0, seq[[e]] = v[[k]]]], {k, 1, Length[v]}]; seq]
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Feb 25 2023
STATUS
approved