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A319710
a(n) = 1 if n is divisible by the square of its smallest prime factor, 0 otherwise.
5
0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 1, 0, 0, 1, 1
OFFSET
1
FORMULA
a(n) = 1 iff A067029(n) > 1.
a(n) = 1 if A020639(n)^2 divides n, otherwise 0.
a(n) = 1 iff n > 1 and A126773(n) = 1.
a(4*n) = a(18*n + 9) = 1. - David A. Corneth, Oct 04 2018
Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = A283071. - Amiram Eldar, Jul 24 2022
MATHEMATICA
Join[{0}, Table[If[Divisible[n, FactorInteger[n][[1, 1]]^2], 1, 0], {n, 2, 130}]] (* Harvey P. Dale, Mar 01 2019 *)
PROG
(PARI) A319710(n) = ((n>1)&&(factor(n)[1, 2]>1));
CROSSREFS
Characteristic function of A283050.
Sequence in context: A319988 A023969 A060039 * A345951 A345952 A359466
KEYWORD
nonn
AUTHOR
Antti Karttunen, Oct 04 2018
STATUS
approved