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A283919
The smallest square referenced in A013929 (Numbers that are not squarefree).
2
4, 4, 9, 4, 4, 9, 4, 4, 25, 9, 4, 4, 4, 4, 4, 9, 4, 49, 25, 4, 9, 4, 4, 9, 4, 4, 4, 25, 4, 4, 9, 4, 4, 9, 4, 4, 49, 9, 4, 4, 4, 4, 4, 9, 4, 121, 4, 25, 9, 4, 4, 9, 4, 4, 4, 49, 4, 25, 4, 9, 4, 4, 9, 4, 4, 169, 9, 4, 25, 4, 4, 4, 4, 9, 4, 4, 9, 4, 4, 9, 4, 4
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Robert Price)
EXAMPLE
A013929(4) = 12, 12 = 2*2*3, so 12 is not squarefree, the square being 2*2 = 4.
MATHEMATICA
s[n_] := If[(pos = Position[(f = FactorInteger[n])[[;; , 2]], _?(# >= 2 &)]) == {}, 1, f[[pos[[1, 1]], 1]]]; Select[Array[s, 250], # > 1 &]^2 (* Amiram Eldar, Nov 14 2020 *)
PROG
(PARI) f(n) = fordiv(n, d, if ((d>1) && issquare(d), return (d))); return (1);
apply(f, select(x->!issquarefree(x), [1..200])) \\ Michel Marcus, Nov 14 2020
CROSSREFS
Sequence in context: A068340 A097667 A202388 * A283670 A019627 A137617
KEYWORD
nonn
AUTHOR
Robert Price, Mar 17 2017
STATUS
approved